So this weekend is the Extra Life fundraiser which is a 24 hour (25 actually 'cause of daylight savings) gaming marathon to raise money for children's hospitals. Many people/teams are raising money for this cause and some have streams where you can go watch.
Rooster Teeth (the people behind the Red vs. Blue series among others) have a live stream that you should check out, they're giving away prizes and of course you can donate.
http://www.youtube.com/watch?v=kjrOuLhO170
Here's the link to the Extra Life website if you want to find out more info:
http://www.extra-life.org/