At the game information screen, select OPTIONS. Then, selected Codes.
Enter one of the following cheatcodes:
Effect - Code
All characters unlocked - STATEYOURNAME
All movies unlocked - DEXTERCROWLEY
All art unlocked - SIRULLY
All combat upgrades - DOGTAGS
All Black Book unlocked - SHARDSOFGLASS
All iPod songs - GRANDMACELIA
All legends unlocked - NINESIX
Level select - IPULATOR
Maximum health - BABYLONTRUST
Maximum skills - VANCEDALLISTER
Unlimited health - MARCUSECKOS
Unlimited skills - FLIPTHESCRIPT
Note: When you enter the code again, it's effect will be disabled.