Reddit, a large social news website (comparable to Slashdot), organised a collaborative charity action at http://blog.reddit.com/2007/12/collaboration-of-geeks-stick-figure.html . I added Wikimedia to the list of charities, and so I urge everyone who has Reddit account to visit http://wired.reddit.com/redditxkcd/?s=new and vote it up.
(I have to add, though, that Redditors seem to not particulary like Wikipedia.)