Infinite Lives:
Enter the following as a password:
LVFRVR

All Weapons:
Enter the following as a password:
PLVRZM

Invincibility:
Enter the following as a password:
MSTSRVV

Infinite Ammo:
Enter the following as a password:
LTSFBLLTS

Invisibility:
Enter the following as a password:
CRSTLCLR

Extra Weapon Power:
During gameplay in multi-player mode collect fifteen of any given weapon.
After you have fifteen, point your weapon at your opponent and enter:
A+B
this does not work with the grenades

All Gangs:
While in the "campaign mode" enter the following as a password:
LTSLTSGNGS

State Street:
Enter the following as a password
CJSKPFLGMH

Storm Ravens Gang:
Enter the following as a password
WMNRSMRTR