Pocket Universe App, Astronomy Made Easy
The app uses the Astronomysensors and the compass to orient your phone to match the real sky. As you turn or tilt the phone, the sky map changes to give you a very accurate picture of where you are pointing, with lots of labels and links to more information. This is one of the first examples of an augmented reality app to hit the platform since the introduction of the 3GS.
Some pictures os Pocket Universe: