Allegiance!
www.freeallegiance.org
When I don't scheme for ascension, I fly in the most awesome space game ever with my friends and rivals. If you ever liked game like Wing Commander (or Elite, for us old timers), you need to check it out.
Published by Microsoft in 2000 they gave up the source code, and us fans run and develop it as a free game. There still hasn't been anything like it.
