1. Angry Birds
Angry Birds has been at the top of the iPhone gaming charts in just about every country in the world, and with good reason. Although fundamentally a simple physics puzzle game, it's incredibly addictive. Think of it as a 2D version of the destructive levels in Boom Blox. Instead of throwing balls though, you twang a variety of different "angry birds" at structures using a catapult. The goal is to destroy the evil pigs that have stolen the birds' eggs in the most efficient way possible. There's a lite version if you want to try it out first, but really there are few better ways to spend time on the iPhone.