Nokia has released a new mobile game that utilizes the digital compass sensor (magnetometer) to the Nokia Ovi store. The game is available for the Nokia N97 and the N97 mini. Here is more info about this mobile game:
Space Impact: Meteor Shield puts you in the seat of Earths last hope to prevent looming apocalypse. You control the gun turret to defend mother Earth against meteorite showers and alien hordes. Use magnetometer to control the turret by rotating the device, take aim and blast the falling rocks to rubble.