Solar System Simulator is a very complete reference tool. The first thing that you will notice when you launch the application is that it shows the orbits of the inner planets of the Solar System. But that is just one of the many things it can show you. There is a little pane that you can open on the right part of the screen which will display all the modes of this application. You can use it to see the orbits of every planet in the Solar System, the orbits of comets and asteroids, the motion of the satellites of Jupiter and other planets, the diurnal an annual motion of celestial bodies, representations of solar and lunar eclipses, and much more. You can freely zoom and pan on any image to see the angle that you want, but the app does a good job of displaying what you should be seeing. One of my favorite views, or modes, was the Galilean Satellites. This mode showed a few of the Jupiter moons orbiting around the planet from side, but centered view.
Solar System Simulator can be used to teach or to learn many concepts about astronomy. For example, the application can show a representation of Kepler's laws.
Unfortunately, this application won't run on Mac OS X Lion. It is a PowerPC app. It runs just fin on Snow Leopard, though.