Free Furniture
On level four where you meet the ghost at the Haunted Shack you can get some free furniture. After you pick the lock and answer all of the ghost's riddles find the hidden cellar outside. There will be some items including a gazing ball when you take it to your house and take it out of your pocket. When you gaze into it your fun, room, and energy will rise.

Unlock Cheats
Unlock the game's cheats by buying them literally from Heidi Shadows, a Sim who sells cheats. She may appear in the following spots:

South and west of Imperial Estates between 2300 and 0000.
North corner of Park Maze between 0300 and 0400.

A slight glitch may allow you to buy a helluva lot more cheats in one fell swoop in the Imperial Gardens location; you buy all the available cheats, scroll the vendor just before she vanishes, wait until 0100 then re-approach the vendor and her wares should be refreshed.