Scriptable simulator of planetary gravitational interactions
This tutorial (italian version) contains the full PDF documentation and VC6/VC.NET source code about a project i wrote some time ago.
This program allows you to grafically simulate gravitational interactions between planet, stars, black holes, asteroids and many other kind of mass bodies.
Its scriptable engine permits to create and describe the behaviour of complex planetary systems, and see the simulation in 3D using OpenGL.