One of my favourite games Labyrinth, is a classic game where you have to control a steel ball in a wooden labyrinth. The Lite edition contains 10 levels while the full version has over 1000 levels and cost a few bucks.
This game shows the great quality and sensitivity of iPhone’s accelerometer, has optional 3d walls and the best of all , it’s free. Also features shadows, incredible physics simulation when the ball is falling into a hole, tactile feedback and a carpenter level with calibration.
Labyrinth Lite is compatible with iPhone, iPod Touch and iPad and requires iOS 3.0 or later and 5.5 MB. You can download for free the Labyrinth Lite version or pay $2.99 for the Labyrinth full version.