The downloadable slot machine is a money cheat. If your Fun motive is low, your odds of winning simoleans are very high.
Playing Catch
If you have two Sims, you can stop a burglar until the cops arrive by getting in their way. Have one of your Sims call the police and the other stand on the tile next to the front door. The burglar will route to the back door (if there is one). Then walk through the house and stand on the tile next to the back door. The burglar will route back to the front door. Repeat until cop shows up. If you only have one door you can still slow down burglars by trying to get in their way, but they will still be able to get through.
Family of Eight
Start an eight-Sim family ... turn "free will" off temporarily ... buy a desk, computer and chair and get each Sim a job ... sell back the desk, computer and chair ... buy a fridge ... turn "free will" back on and play in high speed. Now all you have to do is make sure your Sims go to work each day. No matter how bad a mood they are in, they never lose their jobs -- with eight Sims working you'll earn between $800 and $2000 a day. With only a fridge, the bills will be VERY low and it won't take long to build up a sizeable bank account. When you have enough money, just kill off any extra unwanted Sims.
Tutorial Cheat
This goes along with the idea that the newbie's motives never drop in the tutorial. Turn on "free will" and get Bob and Betty a job. Build up their skills, then put a weight or something on the "3" button on your keyboard. Let the game sit overnight, and when you come back in the morning your Sims will have made plenty of money. The tutorial is the only place in the game where you can let the game sit overnight, and come back to Sims that are still employed. Then if any of the other families in the neighborhood need an extra boost of funds, just kill off Bob or Betty and have your Sim marry the other one. You can then kill off the remaining Newbie and keep all the money.
Moving Up
If you want to start a household with more than one person and want more than just $20k to start out, create each Sim as a separate family, then move one of them into a house and build a nice room. Now move one of the other Sims in next door and give them only a phone. Now have the two Sims develop a relationship and move in together. You can repeat this over and over and end up with a household of eight beginning with $160k.
Wealthy Neighborhood
Importing and exporting: Once you have a family with a healthy amount of cash, that family can be re-imported into your neighborhood multiple times, effectively seeding the game with wealthy families that can be married for fast cash. Just take the .FAM file for the family in question and put multiple copies (just increment the number in the file name) of the .FAM file in the UserData\Import folder.
Take it Back!
Sims can buy a desk, computer and chair. Use them to get a job (there are more available than just the ones in the newspaper) and then sell back the items right away. As long as it is on the same day the Sim bought the items, they will get all of the money back.
Unnecessary Loss
Buy both the fire and burglar alarms to prevent unnecessary losses.
To Catch a Burglar
The best place to put a burglar alarm is where visiting Sims enter and exit the Lot. This can also be an easy way to make some extra cash. Placing the burglar alarms indoors can be iffy because once the burglar starts running, the cop can't catch him. Placing the alarms on a wall segment on the corners of the lot will cause them to go off the second the burglar steps onto the lot. The burglar will get caught every time, and the policewoman will give you $1000 for the catch. (One more thing: Don't bother to call the police if you don't have an alarm; they won't make it before the burglar gets away.)
Use HomeCrafter to Save Money
Using HomeCrafter, Wall and Floor tiles can be imported into the game at a cost of $1, allowing the user to place Floor tiles and Wallpaper for a fraction of the normal cost. Remove the user-created Wall and Floor tile files from the GameData\Walls or GameData\Floors folders and the Wallpaper and Floor tiles will reset to other (more expensive) tiles.
Walls are for Privacy
A lot of money can be saved by not building walls for your Sims. Walls usually only serve to increase the time it takes to get from object to object. The only reasons to build walls are for privacy (the bathroom) and to keep your Sims from waking up by a disturbance in the same room.
