Enter Ctrl-Shift-C in game and enter the cheats.

Cheat code:             Effect:
changelotzoning [residential | community | hotel | ]   
                        Changes the zoning type of one's lot. 
                        MAKE SURE THERE ARE NO SIMS IN THE HOUSEHOLD 
                        BEFORE CHANGING THE TYPE.

AddneighbortoFamilycheat [on/off]     
                        Allows the adding of neighbors 
                        to one's family. [From OFB]

Forcetwins              Forces twins on a pregnant sim.

Plumbbobtoggle [on/off] Hides Plumbbob.

Ctrl+Alt                Wall Placement Restrictions Removed Cheat, 
                        allows anything to be placed anywhere.

familyfunds [name] XXXX It gives a family money. 
                        It may work with people in a household, 
                        though I have not tested it. 
                        [name] - The Sim family last names. 
                        XXXX - Money amount.

roofslopeangle [15-75]  Adjusts roof angle.

showHeadlines [on/off]  Hides the thought, speech, 
                        and ++/-- balloons of Sims. 
                        Best for movie makers.

unlockCareerRewards     Unlocks career rewards for selected sim.

maxMotives              Maxes motive for all sims on lot - 
                        good for sticking around somewhere 
                        that lacks nessecary items, 
                        such as a bathroom.

motiveDecay [on/off]    Disables or enables motive decay. 
                        Goes best with maxMotives.

aspirationPoints [#]    Applies the level selected. 
                        [#] = The level you want.

lockAspiration [on/off] Something like motiveDecay, 
                        stops Aspiration decay.

aspirationLevel [0-5]   Gives tons of aspiration reward points.

agesimscheat on         Shift+click allows you to edit their age.

setLotLightingFile [filename]   
                        Allows you to make a new lighting value 
                        with specific lot values. Useful 
                        in lighting one place but not another.

boolProp allow45DegreeAngleOfRotation [true/false]     
                        Allows you to rotate any object 
                        at an angle.

help                    Shows you a list of cheats. 
                        Help -all may preform better results. 
        
help [cheatname]        Replace [cheatname] with the name of a cheat 
                        for information on the cheat.

exit                    Closes the cheat window.

moveObjects [on/off]    Allows one to place any object anywhere.

aging [on/off]          It disables and enables aging.

autoPatch [on/off]      Tells you if there's a patch for the game.

slowMotion [value]      Swap value for 0-8 with 0 at normal 
                        and 8 at slowest. Slows the game.

boolProp enablePostProcessing true/false       
                        Allows postprocessing cheats, 
                        which are useful for movie makers.

bloom [r g b x]         (rgb is color) (x is the bloom amount) 
                        [0.0 - 1.0]. Adds a blur effect.

vignette [centerX centerY X]  
                        Causes blur from the location specified.

filmGrain [val]         [0.0-1.0] Makes the screen grainy.

letterBox [val]         [0.0-0.4] Adds letterbox effect.