Cheats
Enter these during the opening movie:

All armor, All gems, Max money	Up, Right, L2, L2, Down, R2, R2, Up, Down, R2, L2, Right, Left, Circle, Circle, Circle
Armored car weapon	Press Up, Down, Left, Right, Square, Triangle, Circle
Double Health	Press Up, Up, Left, Left, Right, Right, Circle, Circle, Down
Infinite Ammo	Press Up, Down, Left, Right, Triangle, Up, Down, Left, Right, Square
Unlock Free Roam and Credits	Press Triangle x3, left, square, triangle x3, left, circle
Free Roam Mode	Complete all the main missions in the game
Unlock credits	Finish the first 12 missions