The Lord of the Rings: The Two Towers

All Combo Upgrades
Pause the game, hold all 4 shoulder buttons, and press Triangle, Circle, Triangle, Circle. The sound of a sword will indicate a correct code entry.

Restore Missiles
Pause the game, hold R1, R2, L1, L2, and enter x, down, triangle, up.

Purchase all level 8 attacks
Push and hold L1, L2, R1, and R2. Then press X, X, Down, then Down.

Beat the game and it gives you these codes:
Start a Mission, Pause, and hold in L1, L2, R1, and R2
while pressing the following buttons:
Always Devastating: square, square, circle, circle
Small Ememies: triangle, triangle, X, X
All Upgrades: triangle, circle, triangle, circle
Invulnerable: triangle, square, X, circle
Slo-Mo: triangle, circle, X, square
Infinite Missles: square, circle, X, triangle