Wikipedia
Orbit-Vis
Orbit-Vis is an orbit simulation program which is designed to allow users to simulate a satellite in any orbit around the Earth, and to give the user data on the position and motion of the satellite in both visual and numerical form. It is based on information from the book 'Satellite Orbits - Models, Methods and Applications', and is an example of an orbit propagation program utilising the Kepler Two-body problem for solving elliptical orbits.
It uses the Graphics Device Interface to display the calculated orbit as it progresses.