Here is a truly wonderful mod by the talented Twallan. It is mod that allows you to play with out the CD!.
In order for it to work though you cant use the launcher. You can bu pass the launcher by going to C:\Program Files (x86)\Electronic Arts\The Sims 3\Game\Bin (windows 7) and C:\Program Files\Electronic Arts\The Sims 3\Game\Bin(vista) and scroll down to the bottom of the page and there is an icon called TS3. if you click it the game opens. This mod is great for those that share their Sims 3 games or just don't like using the CD
you can get the mod here