Bughouse
I play a lot of bughouse over the board (OTB) and online on the Free Internet Chess Server (FICS) where my handle is knighttour. Bughouse is a chess variant where 4 people play chess on 2 boards. You have a partner who is the opposite color from you on the other board. Whenever a player takes a piece, he hands it to his partner who can then drop it anywhere on the board as a move. Checkmate on either board wins the game.
Bughouse is far more fun than chess for 3 reasons: 1) it is a very social game with a lot of communication, 2) each game is quite different because the piece flow changes the openings very quickly, and 3) it is always possible to make an even matchup (by partnering a strong player with a weak player and playing two mediocre opponents).
My chess skills are very fishy. I'm rated around 1300, but I haven't played USCF rated games in over 7 years. Eventually I might get back into it and sandbag a big tournament. One of my friends won $20,000 by doing that.
Several times a year I go to chess tournaments such as the World Open to play bughouse in the skittles room. In addition there are gatherings in Las Vegas, San Jose, Berlin, Geneva, etc. where Internet bughouse players congregate for a weekend. I've been to many Vegas gatherings (probably 5-6), but none of the others yet. While I was in Philadelphia I played bughouse monthly at Bob Dodge's house (they've been playing for over 20 years). When working at Cato I would play at the University of Maryland College Park Chess Club. At Rochester Institute of Technology, Auburn University, and San Jose State University I played weekly with the Chess Clubs.
Because of online features I refuse to take advantage of like premove and smartmove (I consider them cheating), I am much better OTB than online. OTB I've held my own with the best players in the world, though I'm certainly a second tier player at best. Online recently I've been simuling a lot so I don't have to deal with partners angry about losing or obsessing over rating points. I've played around 10,000 simul games and 10,000 games with partners online. My total time online is a staggering 548 days, which gives me a percent of life online of 18% since 1998. I never idle... all that time was spent playing games, watching games, or chatting.
My bughouse style is very unique: I'm a defender much more than an attacker... I only attack as a last-ditch counterattack if I'm about to be mated, to win if I see a forced win with a few sacs, or to keep myself in a good position if I can attack without losing trades. In general I try to eat as many pieces as possible and I'm not afraid to walk my king out to the center of the board - or even to the other side of the board. Because I kingwalk so much I know I'm safe even when my position looks very precarious to people unfamiliar with my style, so my opponents often sac a lot of pieces trying to mate me. Those pieces give my partner a huge advantage and give me a winning chess game on my board if my partner is able to sit. I'm usually very fast in the opening, making more deliberative tactical moves in the middlegame.
Some of my games can be viewed on the Variant Chess Database. I'm a moderator on the Bug Board. I was asked to write a chapter for the Bughouse Book, but unfortunately I didn't have time due to my law school workload. I host a number of bughouse websites including the Bug Board, the Bughouse Book, Bughouse.net, etc.