Bolo is a multiplayer tank game originally released on the Mac. Ive tried it but wasnt all that impressed (Dying all the time will do that). There are versions out for windows now so that you can play it on your PC.
http://www.the-underdogs.org/game.php?id=2824(I figured someone should give a sensible answer <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />)
