Unlock Arena Mode:
When you've finished the game go to the 'Extras' menu and Arena mode will be an available option.
Unlock New Goblin as a Playable Character:
This is only available on the Collector's Edition and all you have to do if you have this edition is defeat him in his first battle.
Unlock Black Spider-Man Suit:
When you have finished the game the Black Spider-Man suit will be an available option.
Unlock Venom as a Playable Character:
Collect ALL 100 Metorite pieces which isn't as easy as it sounds.
Added by: Sanzano Sep 27th 2007, ID#232