I'll be honest, at the expense of disagreeing with some of you: I don't really like Angry Birds. Sure, I'll admit it's a quality app, and I obviously can't deny all of those sales. But personally, it's just not my game -- I don't find it nearly as fun as some of the other games on the App Store.
That said, I know plenty of people enjoy Angry Birds, and for those people, Trucks and Skulls will probably scratch the same itch. Gameplay is almost exactly the same, except instead of birds, you're throwing trucks, and instead of pigs, you're attacking ... well, you can probably guess. There are a few new mechanics, a full level maker and screenshot sharing service, and the stages are obviously different, but otherwise, it's more of the physics puzzle goodness that Angry Birds has, only done with a heavy metal, death trucker aesthetic. Heck, maybe that appeals to some of you even more than Rovio's title.
Trucks and Skulls just recently released a free version, and the full game is just US 99 cents on the iPhone and $1.99 on the iPad, with Game Center integration included. If you've already blown through Angry Birds and the recent holiday edition, give Trucks and Skulls a try.