1. For all the weapons and items in the game try this:
l,r,l,l,r,l,r,r,u,d,u,u,d,u,d,d during the game. (L=Left, R=Right, U=Up, D=Down)

2. Passwords... (S=Square, C=Circle, T=Triangle X=X)
30: Air: s,c,x,c,x,t
31: Jump: c,s,x,t,c,t
32: Room 101: t,s,x,c,s,x
33: Firepower: x,x,t,x,x,s
34: Wave: x,c,s,c,c,s
35: Push Off: c,t,x,t,x,t
36: Perimeter: x,t,t,x,x,s
37: Spiral: x,t,t,x,t,s
38: The Castle: s,t,s,t,s,x
39: Fortress: s,x,t,x,x,t
40: Lifts Ahoy: t,x,t,c,s,x
41: Push Me: c,x,t,c,t,s