Crush the Castle for iPhone/iPod Touch is free today (5/5/10). It's a fun catapult game where you destroy formations of people/castles.
I had the Lite version for awhile, but free for the full version was good enough for me to upgrade.
Still playing way too much Sword and Poker, though I wish I could listen to my own music while playing that one. That's the only drawback to it in my opinion.
/tk