In what has become a yearly tradition, the awesome folks at Speed Demos Archive are having a marathon webcast where they do speed runs of all of our favorite videogames and take donations from viewers that they give to the Prevent Cancer Foundation. The January 2012 marathon raised $149,000 for this great cause, and the 2013 event hopes to raise even more.
You can watch the 2013 marathon, which is running from January 6 through January 12 (all day and all night), on Twitch.tv at http://www.twitch.tv/speeddemosarchivesda. You can check out the schedule for the speed runs here - SDA Awesome Games Done Quick 2013 Schedule. This year's marathon features 114 games and includes titles like Shadow Complex (XBLA), Banjo-Kazooie, Super Mario RPG, Fallout, Fallout 2, a ton of Mario, a ton of Sonic, a ton of Mega Man, a ton of Castlevania, and some newer things like Portal 2, Dark Souls, Mass Effect, and more.
Even if you don't donate, this is still a ton of fun to watch. Once again, you can watch on Twitch.tv here - http://www.twitch.tv/speeddemosarchivesda