Open the cheat boxboolprop constrainfloorelevation false a fantastically useful cheat for build mode - allows wall heights to be edited, and floors to be levelled using floor tiles. See New Dogleg for more information on how to use it.
Temporarily makes your sims larger or smaller. I've yet to find a use for this.
After you have played the game a few hundred times, the video on startup can get tedious.
In C:\Program Files\EA GAMES\The Sims 2\TSData\Res\Movies or wherever your base game is installed,
Rename it to Xintro_eng_audio.mov - or anything you like so long as you change it.
Credit to Thomas Riordan of GreenSims 2 for the information
boolProp snapObjectsToGrid true/false may allow you to build to the edges of the lot. Well almost. Use 'false' to place objects out of grid. But still no building on the property line or the line next to it is possible.
boolprop locktiles false may allow you to build right up to the very front of the Lot - ie up to the pavement and roadside.
Open your cheat window on the lot (ctrl-shift-c), type in moveobjects true and you're set. This will even allow you to remove the street tiles if you want. You can lay tiles all the way to edges. You can even put walls up on that tiny strip of grass on the other side of the street. This comes in handy if you want to build a second story overhanging the street. You'll need to place columns (you'll remove these later) at regular intervals on the street for this. I'll offer a bit of caution when building second story homes that hang over the street, however. Building a wall too close to the street on the main side can result in work/school vehicles getting "hung up". You'll have to use the moveobjects cheat to place anything in rooms resulting from this method, but the sims don't seem to mind where it is. Also, remember to turn the cheat off in order to place driveways.
intProp maxNumOfVisitingSims 8 invite more people to your parties
if your dogs can't have puppies, or the wife can't get pregnant...
You can enter these per lot but then they will be temporary; I suggest putting them into the userStartup.cheat file so you can avoid typing them in all the time.
uintProp maxTotalSims [number]
uintProp maxTotalHumans [number]
uintProp maxTotalPets [number]
One of many things it does.
Batbox "Fix Flashing Blue" will also bring up the mirror interface for anyone.