Legends of the Five Rings
I'm currently in and L5R game and am also running one. You can find the page for it here.
Vampire: the Masquerade
I'm currently involved in a number of LARPs involving V:tM, including one I'm running. My favorite clan is Ravnos, whom I play on a regular basis. You can find links to those games here.
Mage: the Acension
I'm not currently in a Mage game right now, but I'm looking to join a couple different games, and even thinking of running one myself. One standing house rule is to ignore Traditions, and we do all the time. But if we don't, I play a Cult of Ectasy.
Werewolf: the Apocalyse
I'm currently helping run a LARP for this game, and am playing in another. I also have a friend who runs a sit down game. I am the guy playing the Fianna all the time...
Advanced Dungeons and Dragons
I'm currently in a game where I play the bard / swashbuckler, and am the tension breaker for the party. I keep the entire group on their toes.
Cyberpunk 2020
I run games when I get a chance, and I try to keep them...well, interesting.
Star Wars
I don't really get a chance to play this, unless you count the LARP I'm in. Check here for details.
I'll try to expand this list and give those of you who are unfamiliar with these games a little background on them later.