Found this really fun game in the Appstore and actually bought it, making that 2 games I've actually purchased for my iPhone. It's a great side-scroller game with an old-school, beat the high score mechanic that's a lot of fun. Between levels you have the opportunity to spend the cash you loot from zombie corpses and abandoned houses on new weapons or upgrades for your current weapons. Visually the game is very similar to Behemoth's work on Alien Hominid and Castle Crashers.
It's simple, fun, and a great way to waste some time while waiting for the bus. Plus, it's like $1.99, so you can't lose.