Easy money
Go to an ATM, then cause a traffic jam to the area. Wait for someone to take money from the ATM, then kill him or her. Make sure to block any nearby roads so the ambulance cannot get to the murdered victim. Take the money they dropped on the ground. Then, run a short distance away, and go back. The money should have respawned on the ground. You can repeat this as many times as desired. You can also kill more people taking their money from the ATM to increase the amount of money that respawns.

Repairing the engine
If the vehicle you are driving breaks down and the engine will not start, call any number from your phone book, and your engine should start again.

Get a Statue of Liberty T-shirt
Go to the statue of liberty and walk up to the second level. Walk through the door (it doesn't swing open, just go through it) and the game will load for a second and you will walk out with a new t-shirt with the statue of liberty on it.

Mr. tasty + GTA Theme Cheat
When inside a Mr. Tasty Ice Cream truck, one of the the songs the truck plays is called the GTA Theme, in a cycle order it is usually played after Flight of the Bumblebee. While playing the song, call ZiT, and a text message will confirm telling you the name of the song. As soon as the message is answered, a Cheat Activated confirmation will appear, and the cheat will appear in the Cheat section in your phone.

Effects: Cheat gives you full healith and Body Armor