Simpsons: Road Rage Cheats

At the Options menu, hold L + R, then enter the codes.

Unlock Soapbox Car - B, B, Y, X
Unlock Mr. Burn's Car - B, B, Y, Y
Unlock Nuclear Bus - B, B, Y, A
More Money - Y, Y, Y, Y
More Camera Views - B, B, B, B
Night Mode - A, A, A, A
Flat Characters - X, X, X, X
Collision Lines - B, B, A, A
Overhead view - X, X, X, Y
Stop time - X, B, Y, A
Slo-Mo Mode - A, X, B, Y
New Year's Krusty - B, B, X, Y (or set the date to Jan 1)
Halloween Bart - B, B, X, A (or set the date to Oct 10)
Thanksgiving Marge - B, B, X, X (or set the date to Nov 22)
Christmas Apu - B, B, X, B (or set the date to Dec 25)

Boat trick
Push any unimportant character in the hole under the pile of rocks by the church. Then go get the boat out of water hole. If the character is still in the hole push boat on top of it and hit the boat a few times and the character will get in the boat. Push boat out of hole then push it around town or put in water hole and it will float around with character still inside the boat.