Infinite Lives:     
     FRTHSTHTTRLSCK

All Weapons:        
     CMGTSMMGGTS

Unlimited Ammo:     
     BLLTSRRFRND

Invincibility:      
     THSSLKSCL

Show Credits:      
     FDTHMGS

Enemies (execpt bosses) won't shoot back:
     SNFFRR

Pin and Ink (turn graphics into black and white line drawings):
     DLKTDR

Gallery (see all the enemies execpt for bosses):
     THBST

Show Credits:
     FDTHMGS

Be invincible without "spirit" affect:
     RBNSMTH

Shows enemies on the map screen:
     NSTHMNDNT

Rainbow colors code:
     LLTHCLRSFTHRNB

Big head with tiny body:
     RBNSMTHDNCHN

     Get just about all the cheats available NTHGTHDGDCRTDTRK

Cut down trees:
     If you shoot some of the tree's they have blue sparks come out of
them.  If they do, take some kind of explosive gun and shoot the tree,
it  will probably fall over (to get the blue sparks I recomend you use
the pistol or the assult rifle)