Ratchet & Clank Up Your Arsenal
Changes quark's outfit
Up, Up, Down, Down, Left, Right, Circle, Circle, Square

Ratchet & Clank Up Your Arsenal
Unlocks Sly 2: Band of Thieves Demo
Hold Down L1+L2+R1+R2 simultaneously at title screen

Ratchet & Clank Up Your Arsenal
Double Bladed Laser Sword
Pause game and enter following for
Circle, Square, Circle, Square, Up, Down, Left, Left

Ratchet & Clank Up Your Arsenal
Unlock Squat Stats
At main menu highlight "Stats" then press Up, Down, Left, Right, Square

Ratchet & Clank Up Your Arsenal:
Pirate Vs Ninja 2 player fight
When choosing level in Quark Vid comics:
press Square instead A, Enter code: _MEGHAN_