Easy Money
Before you load your game activate the cheat menu at the main menu (just press L1+L2+R1+R2 to bring it up). Enter the Freeall and Midas cheats. Now once your game has loaded go to the menu (press start) and select buy. Buy as many Meet Major Domos as you can fit in your garden. Now save your game and reset the console. Load your game, but this time do not activate the Freeall and Midas cheats. Load the game and now sell all the Major Domos. You will get 15,000 simeoleons every time you sell one!
Submitted by Sinead. 100% success rate. 

Cheat Mode
Press L1 + L2 + R1 + R2 at the Main Menu to enable cheat mode. This will let you access the following:

• Midas: Unlock all two player games, all objects and all skins.
• Freeall: All objects cost 0 simoleons.
• Party M: Unlock Party Motel two player game.
• Sims: Unlock the 'Play The Sims' mode without going through the 'Get A Life' dream house.

Go to: The Sims Info Page | nGaming Home Page.