Restore Life:
     Pause  the game, then press L1, R2, L2, R1, Up, Up, Left, Square,
Right, Circle, Start

Shrink Jamgut:
     Pause  the game, then press R2, R2, Circle, R2, L2, L2, Left, L2,
Triangle

Opens Bonus Gallery:
     At  the main menu, press Triangle, Up, Circle, Right, Down, Down,
Square, Left. Repeat the code to unlock more galleries.

Alternate ending:
     Save all the 260 natives to unlock an alternate ending.