The following is from The Sims 3 Game Guide Collector's Edition.

Not sure how many of these are correct. I've heard that a few don't work. The Sims 3 is the first game that I've not used cheats in, so haven't tested them myself. Personally, I don't think you need the cheats - my Sims make enough money very easily, and the greening doesn't take anywhere near the length of time it used to.

To enable the cheats, press Ctrl (Control) + Shift + C at the same time (Windows). Once done, a blue bar will appear at the top of your screen and you can type in the following cheats:

General Cheat Codes: (Command - Effect)

help - Lists all commands available at the moment.
enableLlamas - Gives a message that says, "Llamas enabled."
jokePlease - Posts a random (and silly) joke on-screen.
fullscreen - Toggles between full-screen and windowed modes.
resetSim - Resets the named Sim with neutral motives, no moodlets, and teleports Sim back home.
fps - Toggles framerate indicator in the upper-right corner of the screen.
quit - Exits the game.
TestingCheatsEnabled - Enables cheat functionality.

Money & Lifetime Points: (Command - Effect)

kaching - Adds 1,000 to active household's funds.
motherlode - Adds 50,000 to active household's funds.
freeRealEstate - Ignores the cost when buying a lot for the current game.
shazaam - Gives 2,500 Lifetime Happiness Points to active Sim.

Build & Buy: (Command - Effect)

moveObjects - Removes footprint limitation for all object placement in Buy Mode and Build Mode. Removes limitations placed on hand tool for when objects are in use, or are normally non-movable objects.
constrainFloorElevation - Allows all terrain adjustments regardless of objects, Sims, and other structures on them. Walls, floors, and objects will move with the terrain, allowing you to create sloped walls and floored hills. However, placing new walls/floors will still flatten terrain, and placing objects will still require the terrain to be flat initially if the objects normally require it.
disableSnappingToSlotsOnAlt - When on, objects will not snap to slots while holding Alt.
shazaam - Gives 2,500 Lifetime Happiness Points to active Sim.


Visuals: (Command - Effect)

hideHeadlineEffects - Hides all meters and effects in the game, such as the plumbbob and skill meter.
fadeObjects - Toggles whether objects fade when the camera gets close to them.
slowMotionViz - Puts the game in slow motion. Optional parameter, value 0 = normal speed and 8 = slowest.
snapObjectsToGrid - Toggles how objects snap to the grid. If true is given, behavior is normal. If false is given, then by default, objects do not span to the grid (and holding Alt will snap them to the grid).
snapObjectsToAngle - Toggles how objects rotate. If true is given, behavior is normal. If false is given, then by default, objects do not span to 45 degree angles when rotating them (and holding Alt will snap them to the 45 degree angles).

Sims: (Command - Effect)

Modify Traits - Interaction to bring up a trait-modification windows. Can set/clear traits.
Add to Household - Add the active Sim to the current household.
Set Age - Set the age of the Sim.
Edit in CAS - Takes the Sim back into Create A Sim and allows you to make physical and personality changes.

Career Buildings: (Command - Effect)

Force Opportunity - Click on carrer building you work at to force an opportunity.
Force Event - Click on a career building to give you a random career event.
Force All Events - Click on career building to display all events for the career consecutively.

Mailbox: (Command - Effect)

Force Service Sim... - Force a specific Service Sim to show up.
Force Visitor - Force a neighbor to show up.
Make Me Know Everyone - Make the selected Sim know every other Sim that exists in the town. Set them to acquaintances.
Make Friends For Me - Make a few random friends for the selected Sim.
Set Career... - Give the selected Sim any career at any level.
Make Happy - Set the mood/moodlets of everyone in the house to perfect. Remove all negative moodlets.
Make Motives Static/Dynamic - Make motives static/dynamic for the entire household.

Information regarding cheat codes by members of the official Sims 3 Forums:

Petreak wrote:

I have tested some of the cheats and I have some info you might find interesting. You might want to update the list.

"TestingCheatsEnabled"
You need to put True on the end of it for it to work. Like this:
TestingCheatsEnabled True
and to turn it off replace True with False.

"shazaam"
That cheat doesn't seem to do anything for me at all.

"Edit in CAS"
I really need this cheat, but I can't get it to work at all. Anyone have any luck?

"Modify Traits"
Doesn't seem to work, but if you have TestingCheatsEnabled turned on, you just hold down the Shift key and left click your mouse button on your Sim and you get the option to Modify Sims's Traits.

"Set Age"
Doesn't seem to work, but if you have TestingCheatsEnabled turned on, you just hold down the Shift key and left click your mouse button on your Sim and you get the option to Trigger Age Transition on your Sim.

"Mailbox:"
The stuff for the mailbox only shows up if you have TestingCheatsEnabled turned on.

"Teleport"
This isn't an actual cheat code. If you have TestingCheatsEnabled turned on and if you hold the Shift key and left click your mouse button anywhere, you will get a Teleport option instead of the Go Here option. Comes in handy for getting around fast.

"familyfunds"
Here is a code to set your family up with as much money as you want.
This is an example of how to use it.
Say you have a family named the Brown family. While you are in their house, go into the cheat window and type this:

familyfunds Brown 1000000

Your money will change to that amount. Just replace Brown with the family's last name and replace 1000000 with what ever amount you want.

I'll keep playing around and see what else I figure out.