Anyone who likes space sims such as Freelancer should give FreeSpace 2 a try. You can buy a copy at Good Old Games for about 6 bucks or so. Anyone who DOES have it or will get it should also give FreeSpace Open a try, which uses the game's source code project to add vast improvements to gameplay and graphics, though it still allows players to use the original graphics so that nobody has any technical difficulties in the middle of the action.
Finally, I WANT ALL FREESPACE FANS TO VOUCH FOR THIS GAME'S SUPPORT ON THE FORUMS HERE:
http://www.xfire.com/xf/modules.php?name=Forums&file=viewtopic&t=57939


This is partly because I'd love to organize massive battles via X-fire... you do know that there are still people trying to play this old game, right? I'm trying to expand its player base and increase probability of a multiplayer game... ...that being said, it's hard to organize a game.

For more info on this game, here is a definitive wiki, mod center, etc. blah blah blah. blah blah blah blah blah blah blah:
http://www.hard-light.net