Although this isn't exactly a traditional space combat simulator, the Homeworld series has always done a decent job of presenting space ships and space combat in a fun way. The official Sierra site has plenty of pictures and information on the game if you're into a more real time strategy oriented experience. The original Homeworld was also the basis for the neat Fleet Action mod. You can download the Homeworld 2 demo here and access community forums for the game here. Homeworld is set to be released in the US in the middle of next week.