Preorder Popcap's Plants vs. Zombies for $9.99 and get a free copy of Heavy Weapon Deluxe.
http://store.steampowered.com/app/3590/
Game is due to be released on May 5.
Looks like a fun game based on the trailer. Just purchased one for myself.
http://www.youtube.com/watch?v=0N1_0SUGlDQ