Orbitron

Orbitron is a satellite tracking system for radio amateur and observing purposes. It's also used by weather professionals, satellite communication users, astronomers, UFO hobbyist and even astrologers.

Application shows the positions of satellites at any given moment (in real or simulated time). It's FREE (Cardware) and it's probably one of the easiest and most powerful satellite trackers, according to opinions of thousands of users from all over the world.