Sims can now invite every played Sim in your game regardless of whether they have already met them. They cannot invite unplayed Sims to partys though. Especially recommended for rotational gameplay.
Beware! If you do not have any other played Sims except your played household, you will not be able to invite anyone to a party. If you want to be able to invite any played and unplayed Sim, use the file partyinvite_anysim instead.
The anyplayedsim module is specifically designed for players which play rotationally and want their played Sims to stay among themselves, but do not want to have to scroll for ages to find their Sims in the menu of the invite_any_sim Mod linked above.
partyinvite_moresims was formely called inviteguesttweak. It will allow you to invite any Sim your Sim has already met, plus relatives, neighbours and coworkers regardless of whether they have yet met them.
partyinvite_playdate_anytoddler Sims can invite any toddler to playdates regardless of whether they know them or not.

Mean and evil social interactions do no longer count towards the goal of interacting ten times with your date.

Complete overhaul of (almost) everything wrong with conversations in TS4.

clean pie menu: Fixes pie menu oversights after the pie menu recategorization and also tunes down the frequence of some interactions that tend to clutter up your pie menu. Each interaction has its own file. Don't forget to delete the files/folders for packs you do not own, otherwise you'll end up with blank text strings. I expecially recommend preferencecategorytweak as that one adds pie menu icons for hobby and activity interactions so that they are easier to be found.
LessAutonomousHuggingAndGreeting – The mod will reduce autonomous hugging and greeting.
LessIdleChat – The mod will limit idle chat to NPCs in unimportant roles.
fewerautonomousintroductions – Sims will introduce themselves less autonomously, especially flirty and enchanting introduction. Together with the 3 'lessrandom' modules, this mod will help with the issue of strangers intruding your Sims' private conversations.
lessmusicalchairs – Sims will change seats less while talking.
lessrandomflirting – Prevents Sims from mindlessly flirting with everyone even though they're already in a relationship.
lessrandommean – Sims will be less mean to Sims they like.
lessrandomfriendly - Sims will no longer be always friendly to Sims they don't like. The will also no longer force funny interactions onto Sims who dislike Comedy - that is, the will take their preferences into account when their friendship level is high enough (btw, the lessrandommean-module does the same for mischief interactions).
morediversespeechandthoughbubbles - adds a lot more diversity for speech and thought bubbles during conversations. Sims will also tend to talk an think about things that recently happend to them, like their birthday, engagement, rejected proposal, recent child birh, promotion, job loss...
morereconcile: The reconcile interactions will be available in more situations now.
miscellaneous:
deepconversation: In true Sims 1 fashion, Sims will talk longer when they have a deep conversation.
hairjokestomischief: Puts hair jokes into the mischief category where they belonged from the stark.
noautolovinghug: Sims will no longer randomly give their loved ones the Parenthood auto loving hug, because I just found it so annoying how excessively this interaction is used.
simpletopics_more: Enhances the visibility of the more common interactions ask about day, compliment outfit and gossip.
criticizewoohootechniques: The criticize woohoo techniques interactions will be available in more situations (found under arguments). Also fixes various bugs where Sims would get conflicting buffs from woohoo.

This is an overhaul of the EA want system which enhances the chances for family based wants and tunes down wants to buy new stuff. Special wants for: pregnancy, elder life stage, childhood phases, lifestyles, preferences, careers...
Note: Only install the packages for which you own the required packs.
There's also a brand new feartweaks module which can be used as a standalone and makes fears less frequent. It also fixes the issue with the fear of the dark not properly going away.

Contains 3 freely combinable mods that tweak bed upgrades.
toddler: Toddler beds can be upgraded to give more energy.
money: Bed upgrades will cost money, but the skill level required is reduced to 2/3.
monster: Upgraded beds will spawn less monsters at night.

This mods tweaks the existing traits to make them more meaningful. Sims will do better or worse in certain/all careers, at school and/or at university based on their traits. Traits will also influence autonomy and skill gain. They will moreover affect how well two Sims will get along with other Sims, this will also be affected by the other Sims mood and/or age. Some of the negative moodlets have been doubled to make them more visible. Positive and negative trait moodlets may affect how fast your Sims gain skills/relationships in either direction. Sims with certain traits will get more aspiration points from fulfilling whims. Traits may also affect reading and crafting speed.

Complete overhaul for visits and phone calls. Mix and match however you like according to your owned packs.

BASE GAME MODULES:
barnights - Less bar night invites.
basecalls - Less phone spam, for instance new friend calls. Other phone calls have been fixed and/or chances enhances, e. g. play hooky, playdate, promotion party. Ghost will no longer call your Sims.
behave - More appropriate visitor behaviour (no bathing, computer or reading books). Sims will no longer instantly leave after they invited your Sim out.
dates - No more date offers from Sims that don't have any romantic interest towards your Sim.
doorknocker - Less door knockers - tuned by taking into account relationship, the mood the Sim was when they left after their last visit and the visitors traits.
morevenues - Your Sim can be invited to a broader variety of community venues.

PACK SPECIFIC MODULES:
badreputation - For Get Famous. Less phone calls for Sims with a bad reputation.
goodreputation - For Get Famous. Less phone calls for Sims with a good reputation, especially less and more appropriate job offers.
challenge - Requires Get Famous. This module adds so called challenge called which you can either accept or deny. Denial will have no consequences at all, while if you accept your Sim will loose a random amount of money (5.000-100.000 Simoleons).
getfamous - For Get Famous. Less donation calls, fame visits and other fame based calls.
cityinvies - For City Living. Higher chance to get invited to opera, karaoke events for Sims with the appropriate traits/preferences.
festivals - For City Living. Festival invitations will better suit your Sims mood and preference.
ecoliving - For Eco Living. Less phone spam, more interesting calls. Weird stuff like pregnant men after phone calls or your Sims parents calling to ask whether they should have a baby have been cut.
gettogether - For Get Together. More invitations to bluffs, ruins, …, less club base phone calls.
islandfoodvisits - For Island Living. Sims will bring tropical veggies instead of pork.
magicduel - For Realm of Magic. Less duel invitations in tims when your Sims not feeling good.
novampires - For the Vampire GP. No more vampire phone calls and visits.
onsiegifts - For Nifty Nitting. Sims will receive 2 baby onesies in their inventory when they are called for congratulations on their new baby.
restaurants - For Dine Out. Your Sims will only get invited to restaurants when they are neither full not already too hungry or tired.

Two sepearate mods that will stop your Sims obsession with figure painting (Discover University) and the child activity table.

Festival notificationd will be silent notifications.

Disables the City Living and Snowy Escape festival notifications.

Sims will autonomously use the toilet and eat eat work even if these needs are not desperately in the red. They´ll also socialise a bit an gain some energy during their breaks. Enhances the chances of Sims actually eating their sack lunch at work. Whenever a Sim eats during work/school, household funds will be reduced by 12 Simoleons.
The separate mod package "TakeItEasy" let's your Sim's motives (esp. hunger and bladder) go up when they choose this at work action. It is thus a workaround for when you don't stay at home while some of your Sims are at work/school. By default, they will not be able to take care of any of their need while you're away from your home lot.

Adds new away actions for skills that have been forgotten by EA (including some hidden ones and all toddler skills). Also adds an option to do homework (also for University) from off lot.
Sims will also fulfill their daily career task when told to level a skill that is crucial for their job (like writing for writers, all instruments + singing and comedy for the entertainer career, mixing + baking + cooking and gourmet cooking for the culinary career ...).

Includes two separate packages. One allows for aging of pregnant Sims. The other on adds an idle to pregnant Sims so that they will occasionally rub their tummy (Cool Kitchen Stuffpack required).

Friendships will decay faster with this mod. The mod also tweaks the friendship stats so that you will need higher values to become friends (50 instead of 35) and good friends (90 instead of 60).
It also adds icons so that you can easily determine who your Sim's friends are.

Fixes the EA bug that lets only the victim of a mean social apologize instead of the Sim beeing mean.

Sims that have recently given birth can enthuse about the event. The male parent can do the same. Sims can now enthuse about the event when they are newly engaged or just married.
They also can have a 'pleasant conversation' with their friends instead of the 'get to know' interaction.

Restores the option to add Sims to ensembles during an event (e. g. parties).

Prevents the pop-ups asking whether your Sim wants to acquire a preference.
(Former name: npcsdontgainpreferences)

Bookcases and storage chests will have their own inventories with this mod.
Important note: When you first install the mod, the inventory of bookcases and storage chest will be empty so make sure you save the treasures you want to keep somewhere else prior to installation!

-Main module: Sims will build positive relationships faster with Sims that share their likes and slower with Sims who don't. Als tweaks preference autonomy a little.
-comedymischief module: Sims will be less likely to perform comedy/mischief socials on Sims who dislike them. Can be used as a standalone.
-discussinterests module: Just like in TS 2, Sims will now actually talk about their interest when discussing interests and other Sims will react accordingly. This module goes very well with my conversationtweak_morediversespeechandthoughtbubbles. Can be used as a standalone.

Note: I do not recommend the main module of this mod for low computer specs (the two other modules are just fine). If in doubt, just try out to see if it slows down your game considerably.

Woodworking will increase your Sims muscles (not fitness skill, just muscle definition).

Contains two freely combinable mod: One assigns school project randomly instead of each Monday to all pupils.
The other gets rid of Parenting Chance Cards and reduces the likelihood of the other school Chance Cards. Note that if you install the chancecards package your Sims will switch to a weather based outfit when they go to school.

Sims can ask to be just friends after breaking up a relationship or divorce. This will fix the negative relationship. The can no longer ask to be just friends without breaking up first. The denouncefriedshiptweak module adds a massive friendship loss to the mean denounce friendship social (this will come in handy for your closeknit Sims to not loose their lifestyle).

Sims do no longer have to be in the business career to invest. The also can invest larger sums (2.500, 10.000 und 50.000).

Enables the regular shower option for energized Sims so they will not fail to complete their morning routine just because they can’t perform the shower interactions you queued up for them because they are getting energized.

More toddlers, children and teens will visit parks with this mod. They will come with their relatives. The effect is stronger on child friendly lots.
There are also modules for some other venues (pools, eco venues, reccenters included.

Sims will read longer before they stop. This affects all kinds of books, included skill books.
There's also a second mod (longerreadbook_tochild) that will make the 'read to child' interaction last longer.

Tweaks the odds so that the chance to develop a positve sentiment is higher and the chance to develop a negative sentiment lower when Sims have a very good relationship or are relatives.
There's also a small package (noyouthfestivalunblessedsentiment) included that stops child Sims from getting a negative sentiment because they feel they have not been blessed enough at the festival of youth.

Socializing with coworkers and classmates will result in a higher relationship boost with this mod.

Adds a sound and text notification whenever a visitor stops by (original mod by BraveSim).

Small telescopes can be used inside. However, you will need to use the move objects on cheat to place them inside.

Restores the destroy object cheat: Sims can destroy objects by shift clicking on them. You can use this mod to destroy stinky leaf piles, coffee left in the streets of San Myshuno, pet poo, struck objects floating in midair, violins about to be used by noisy roommates, dirty dishes, garbage plants and much more.

Sims will react to the death of aquaintances, not so close relatives, disliked sims,... less strong as they do without this mod. The moodlets are shortened and less strong.
The nophonenotification package stops other Sims from calling you to tell that a Sim has died.

Sims with level seven creativity can write a doll house story at the PC with any posive doll house moodlet.

Sims can now also purchase books from bookcases on Community lots.

Friendly and funny interactions will have a higher chance of failing between Sims with bad compatibilty (Growing Together).

Romance socials will have a higher chance of failing between Sims with low attraction levels (Lovestruck).

You don't need both packs to use this mod.

Milk will fill your toddlers hunger motive faster than other drinks.

Adds more choices to add fish to aquariums. You can buy any fish you desire from those aquariums that can stock 6 fishes.

A tiny mod that makes the hire vendor interaction charge free and immediate for a smoother Community Lot Experience.

Sims will be able to ask other Sims what happend after some events (like cheating, divorce, negative pregnancy test).

Adds more animations for the interactions "Ask to leave" and "Invite in".
Version 1 is Base Game compatible.
Version 2 requires the Expansion Packs Get Together and Parenthood.
Only install 1 version.

The lock door for everyone interaction will alsways show up on the first page of the lock door pie menu with this mod.

Makes the bassinet draggable in live mode so you can keep your baby near your Sims without having to enter build mode. The optional 2nd package includes texture overrides for the 4 bassinet colours.

Fixes the bug where most Sims will be greyed out in the travel with picker.

Swimming enhances the motives fun and hygiene.
With the 'nofatloss'-version of the mod, Sims will not loose fat while swimming.
Make sure to only download 1 version.

Disables the endlessly repeated trait notifications on the pinboard.

Contains three different, freely combinable mods to give your gardening Sims more to do again: watering, evoling and weeds. The evolve package will let you evolve your plants sooner if you fertilize them on a regular basis. The fertilize package will let you fertilize your plants more often and reenable pet poop as a proper fertilizer.

Contains 2 freely combinable mods that enhance romantic relationships.
holdhands - Holding hands with another Sim may now result in surprisingly engaging reactions (first kiss, go steady and proposal by the target Sim, share big news), if your Sims are in the right mood.
ParenthoodGP - Parenthood GP is obviously required for this one. Unlocks the ask for future plans and deep personal conversation interactions during dates as between soulmates (and best friends). If you are getting blank text messages, remove the file sims4me_romancematters_ParenthoodGP_textmessages, as the text messages do actually require various packs to work.
confessattraction - obsolete
askifsinglefix - obsolete

Makes the adult lifespan last 20% longer so your Sims can actually fully raise their kids before they die.

Well treated sims have a chance of not dying of old age even when their life bar ist full.

Only sad Sims can autonomously mourn at tombstones with this mod. Restores the option to mourn at gravestones even if the stored sim has been sent to the netherworld. Performing the special Day of the Death interaction on tombstones fulfills the remembrance holiday goal.

Emotion drinks can now also lead to useful buffs.

Sims can now reach the 10th level of rocketscience from reading the advanced skill book.

The game will less often prompt your Sim to change their traits to romantic, unflirty, lovebug and romantically reserved.

Teens and kids will gain character values when performing certain interactions with their younger siblings (mainly babys). Based on character and a good deal of randomness, Sims can get positve or negative moodlets from interacting with a baby.
Sims will also be more sensible in autonomously taking care of their baby's needs.

Sims will be able to congratulate other Sims which recently had their birthday, engagement, wedding or found a new partner.

You do no longer have to greet Sims intruding on your conversations before being able to bid them goodbye.
If you Sim already knows the Sim, you find the interaction in the 'actions' submenu.

Mod for rotational playstyle: When you have two teenagers who are either significant others or promised to each other, they will now be able to do some romance interactions when one of them ages up to young adult. Note: The kissing and make out animations are a little off (see picture), so there are addon packages to disable these for your teen-young adult couples.

Taking a nap will boost energy a little more for toddlers.

Fixes the plopsy feature not working on appartment lots and rental los.

With this mod, the High School Years ice cream stand, the Snowy Escape climbing rocks and the invisible dance floors for Get Together can be found in buy mode.

Sims will no longer brush their teeth while eating.

As there is now much more stuff available on Plopsy than in the beginning, I significantly raised the number of offers that are available at the same time.

Fixes a small bug that made Sims hardly able to write bestsellers.

All Sims can now revive plants if the pay 1.000 Simoleons. Payment is reduced if they have gardening specific traits/skills.

All kinds of partys count towards the party aspiration goals.

Gets rid of almost all of the restrictions for pregnant Sims, except for using hot tubs.

If you give the 'near good schools' lot trait to a library, club, pool, lounge, forest park, cafe, natural pool, karaoke bar or arts center, a lot more teens will visit that lot.

Enables the sadness hotline for sad kids.

If you tend to click the wrong option and confound the 'bring here' and 'switch to zone' interactions, fear no more. This mod add different icons to the interactions to avoid this misfortune.

Sims can change the card table from cards to the lama game and back instantly.

Adds a new interaction to the action pie menu where your Sim can ask another Sim to invite one or more Sims that are special to that Sim over for a visit. Special Sims available are: family members, significant other, best friend/confidant and owned pets.

Fixes a bug where toddlers cannot talk to other Sims they have not yet met.

Tweaks the behaviour of jealous sims to make them less annoying.

Fixes the 'polish to perfection' string on chess tables and also makes it so that only neat and proper Sims will see that text string in general. Slob Sims will also get their own cleaning text string.

Contains three mods:
noidles - Sims will not yawn or do the inspired idle when reacting to decorated environment.
reducedbuffs - The moodlets Sims get from being in a good environment will not last as long.
noidlesandbuffs - Idles and moodlets from badly/nicely decorated environment will no longer occur at all.

Sims will be more likely to not put their books down on the dining table. They also will be less likely to do their homework on top of their computer's keypad.
The dishes-Module stops Sims from putting down their dishes in places where they cannot reach them when trying to clean them up.

Sims can now refill their minor pet's food at any time, not only when your pet is already close to starving.

Adds a positive moodlet from sharing big news not only to the father of the child, but also to other siblings.

Cooking, sleeping and such will no longer be judged as inappropriate when your Sim visits near relatives or good friends. Sims will also not find your Sim's behavior inappropriate when they first show their gratitude to the host (good manners trait), as long as the buffs are active. A toddler's behaviour will never been seen as inappropriate.

With this mod, muscles will build half as fast as before. Fat changes remain unchanged.

Sims will no longer feel unconfortable because of outdoor puddles.

Disables the interaction to uproot plants.

Fixes a bug in the freelancer career. Your Sims' work will no longer be continuously rejected despite editing. There still remains a chance of failure though.

There are less elders showing up at the lounge with this mod.

Enhances the chances of Sims having a conversation to actually face each other.

Gets rid of the buggy thalassophobia feature.
thalassophobiafix just fixes the buggy buffs.
Only install 1 file.

Chatting and text messaging on the phone gives a higher friendship boost.

Disables the most common sentiment text messages.

If your Sims send a love email, there is now a chance that your crush will invite you for a date as a reaction.

Adds more variety to the presents your Sims are gifted after a successful wedding party.
Note: This mod requires a lot of packs, but you cannot use it with MyWeddingStories as the pack disables the former feature of getting wedding presents.

Booklearning for the skills herbalism and baking will be faster than usual.
You can request more skills to be added. I thought those two to bei the most tedious to learn from just doing practise.

The capsules containing MySims figures can now be extracted directly from the inventory without having to wait for your Sim just like fossils, seed packages and such.

Reduces the panic moodlet when a Sim goes into labour.

Replaces the toy duck with a crab toy ball for the kiddie pool (Cats & Dogs EP required) and a sea shell for the ocean.
There's a separate file for each.

As Neia (MTS) has not updated her fabulous no relationship culling mod any longer, I made this very simple mod to prevent relationships of played Sims to be culled unless there are more than 350 (previously 35).