There are a lot of cheats Esther1981, and in fact, you can see where the ones in Sims 3 came from
(If you go back to Sims 1, there is a definite lineage)
Here are some more minor ones. I do believe you have to enable the cheats with the following first:
Open the cheat menu by pressing Ctrl + Shift + C, then entering the following:
boolProp testingCheatsEnabled true
If you wish to access outfits, hairstyles, etc. used by NPCs in the game, or otherwise locked outfits (like career ones...I always loved the Paranormal shaman outfit), then while in Create - A - Sim, press Shift + N to access the outfits. Press Shift + M to disable the outfits.
For what we would consider normal cheats:
Press CTRL + SHIFT + C to access the cheat window
Cheat - Effect
motherlode - Gives 50,000 Simoleans
aging off - turns off aging
aging on - turns on aging
unlockcareerrewards - allows you to access all career rewards