Some Codes to unlock pictures in Code Unlockables (these passwords are entered on the Extras menu using the d-pad or either control stick):
R,R,U,U,L,L,U,U - Unlock one picture
R,R,R,R,D,D,L,L - Unlock one picture
U,L,U,R,U,L,U,R - Unlock one picture
U,U,U,D,D,D,L,R - Unlock one picture
D,D,D,D,L,L,L,L - Unlock one picture
All Wingmen Cheat:
Complete the game under normal difficulty.