The Humble Indie Bundle #3 (Frozenbyte) is now available.
humblebundle.com
humblebundle.com
The pack's worth $10 or more for Trine alone - three-player co-op that involves everyone yelling and panicking at each other trying to solve puzzles and not get killed by enemies. Good times. I don't have as much experience with Shadowgrounds co-op, but they're both cool top-down shooters - not as insane as the Alien Shooter series, but with much more polish.
edit: the email arrived a bit late, now downloading...