Celestia: A 3D Space Simulator. Wow I was browsing through Sourceforge and went through the most downloaded open projects. Found this incredible viewer of celestrial bodies. Amazing what people have built. It works great and I can't wait to show it to the kids. Nice thing is that it is tied to various public databases around the world so that you can actually travel to a star (like Star Trek!) and then right click to get the actual real information about it. A geek's toy for sure.