First thing: sorry because I am not logged in, but forgot my pass and I just found this cheat so I wanted to sumbit this right now!
1. Tired of Sims who need to rest, when you want to build up some skills? Tired of Sims who need to take Shower or Bath after building the Body Skill? Tired to clean up after you eat? Then why not press Ctrl+Shift+C and type maxmotives? It will let your Sims to...well, just try it! It's extremely useful!
2. Want to take control over the Pets? Then use this cool cheats: boolprop controlpets on and after that boolprop petactioncancel true.
Note on the cheat 2.
Boolprop petactioncancel true gives you the ability to cancel the Pets actions and boolprop controlpets on gives you fully direct control over the Pets...um...your Pets

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Note on the cheat 1.
This cheat is very useful, and works at all the other expansion packs! But after a while you will need to type it again! I am not sure if it works at The Sims 2 with no expansion packs attached to it, but try it!
NOTE: If you want more cheats, contact me on my e-mail adress...