Yeah, it's been done. Everyone's got it, played it, sworn at the f$&king pigs and moved on. But if we're talking about the truly awesome apps for the iPhone here with iAppalooza, how can we not recommend this?
The story goes something like this: Pigs steal bird eggs. Birds get angry. Birds throw themselves at pigs to kill them using a giant catapult. There are currently 195 levels included in the game, which is hours upon hours of awesome frustration at those hideous little pigs.
A quick check of the game's page on iTunes shows that it has 29030 five star ratings. That should say everything there is to say right there. If you haven't played this, spend the $1.19 and start today. It's even got Retina display support and Game Center achievements now.