Contra

Codes

30 Lives	At the Title Screen press Up, Up, Down, Down, Left, Right, Left, Right, B, A, Start.
Sound Mode (JPN Only)	At the title screen, press and hold the A & B buttons simultaneously and push Start.
Steal life from partner	If you die in a two player game, hold down A and B simultaneously

Game Genie Codes

SLAIUZ     Start with infinite lives

GXIIUX     Keep weapons after losing a life 

SLTIYG     Become invincible-- enemies don't shoot at you

PEIIXZ     Start new life with machine gun

ZEIIXZ     Start new life with flame-thrower

LEIIXZ     Start new life with spread gun

GEIIXZ     Start new life with laser