Using the arrow keys or gamepad type in the following codes at the Code menu in the game options. Type in the code again to disable the effect.

Unlock ALL Levels:
Ipulator

Unlock ALL Combat Upgrades:
Dogtags

Activate Infinite Health:
Marcuseckos

Activate Infinite Skillz:
Flipthescript

Max out the Health Meter:
Babylontrust

Max out the Skills Meter:
Vancedallister

Unlock ALL Beat Down Arenas:
Workbitches

Unlock ALL Beat Down Characters:
Stateyourname

Unlock ALL Black Book Graffiti and the Truth Pieces:
Shardsofglass

Unlock ALL Legends:
Ninesix

Unlock ALL Movies:
Dextercrowley

Unlock ALL Concept Art:
Sirully

Unlock ALL iPod songs:
Grandmacelia