If for some reason you still haven't tried out the co-op goodness that is Crackdown, now is your chance to get in on the action for only $10. Amazon.com is having their deal of the day and Crackdown is marked down from it's normal $30 price point.
Crackdown features two player online co-op through the game's story mode. Along with that there's various races, mini-games, jumps, orb collecting, and just general tom-foolery to be had. Yes, the game has tom-foolery - it's a bullet point on the box.
Update: And it's sold out!