TS3 Creator's Camp: Day 3, 17:15
Just time to throw something completely new into the mix!
The Sims 3 has a Party Planner for your Sims! When a Sim uses a phone to throw a party the Party Planner screen pops up. Here you can choose which kind of party it should be (currently just House Party or Birthday Party), the day and time the party should start and the dress code. You can opt to have all your sims arrive in casual clothing, formalwear or swimwear. Then you just add the friends you want to attend in the invite list.
Of course not all guests will turn up but later in the game you can acquire the status of "Legendary Host", guaranteeing that all of your invites will be gratefully accepted with attendance guaranteed.
Party on!
/Steve