To bring up the cheat window, press Ctrl, Shift and C at the same time. Only a few of these cheats are directly helpful to the game, a lot were made for the developers of the game.

klapaucius - 1000 Simoleons (Only useful is you have NO expansion packs and HAVE NOT updated your game to version 1.1 using the patch)

rosebud - 1000 Simoleons (Use if you have patched your original game or have any expansion packs) 

water_tool - Enables the water tool, which is NOT the swimming pool tool

interests - View selected sim's interests. In Hot Date or Vacation/On Holiday, interests can be seen in the panel at the bottom of the screen.

autonomy - (Values 1 - 100) How much the selected Sim will act on their own

grow_grass - (Values 1 - 150) How long the grass in the area surrounding your home is

map_edit on - Lays a grid over the game. When you click on a square, it will turn on or off. An active square allows you to make changes to it, and inactive square is usually used for roads, paths, etc.

map_edit off - Turns the above feature off

move_objects on - Lets you move the mail box, rubbish bin outside etc.

move_objects off - Turns the above feature off

route_ballons on - For developers, not too sure what it's supposed to do.

route_ballons off - Turns the above feature off

sweep - Shows the "ticks" in the game. Type again to turn off

draw_all_frames - Draws all of the frames in the game, may slow the game down

tile_info - Information on the selected tile

set_hour - (Values 1 - 24) Lets you choose the hour in the day you want

sim_speed - (Values -1000 - +1000) How fast your sims move

! - Repeats the last cheat

!;!;!;!;!;!;!;!;!;!;! - In the case of the rosebud or klapaucius cheat, each !; is 1000 Simoleons