This DIY satellite tracking project takes a stock Pelco rotator and controls it with an Arduino 2560 using relays, a magnetometer and an accelerometer. The Arduino receives the satellite position via Orbiton and a custom serial driver over USB. It's designed to be used with a 2m/70cm antenna for HAM radio operation, but can be used for many satellite tracking needs.
Most of the information to build your own system is on this page and it's an open source project. Please feel free to contact me regarding questions or enhancements to share with the maker and HAM community. If you have an interesting build related to RF, let me know about it!
Russ Morris WQ0N