Smogon Live Wifi Tournaments
The Smogon Live Tournaments are a weekly series of fun quick tournaments that focus around Nintendo's VGC rulesets, though that is not all that is played. For the January 2011 - March 2011 Season the metagames are 2009 VGC, 2010 VGC, 2011 VGC, and 6v6 OU.
To sign up for a Smogon Live Tournament all you need to do is be in #smogonwifi and pm the host of the tournament your friend code. Registration will start 10 minutes prior to the listed starting time, and last until 10 minutes after. There is no limit to the number of players, and the tournament style will accommodate the size of the tournament.