Alternate Outfit for Spiderman
Description: unlock "Project Carnage", which will allow you to choose between Spiderman in a red outfit or a black outfit
How to unlock: beat the game once through. Now, find Nick Fury at the main hub during a subsequent playthrough and approach the computer when he tells you to.

Characters (and more!)
Use the following cheat codes on the helicarrier (in between missions) to unlock cheat:

5,000 Tokens	Up, Up, Down, Down, Left, Right
Green Goblin	Left, Down, Right, Right, Down, Left
Sandman	Right, Right, Right, Up, Down, Left
Venom	Left, Left, Right, Up, Down, Down

Story Mode Characters
Black Cat, Blade, Doctor Octopus, Green Goblin, Iron Fist, Rhino, Sandman, Venom
Those characters can be unlocked once they are encountered and defeated during Story Mode