Here are some cheats noone has mentioned yet
Go to options and hold the left & right triggers while entering the cheats.
Thanksgiving marge: B,B,X,X
String mode: B,B,A,A
Paper people: X,X,X,X
Halloween Bart: B,B,X,A
Christmas Apu: B,B,X,B
We have more cheats and tips for this game here, The Simpsons Road Rage cheats
Comments for this cheat