Quick list of games-related charities via GamePolitics.com:

[LIST]
[*][URL=http://www.ablegamers.com]AbleGamers[/URL]
[*][URL=http://www.blueredefined.org/]Blue Redefine[/URL]
[*][URL=http://www.childsplaycharity.org/index.php]Child's Play Charity[/URL]
[*][URL=http://folding.stanford.edu/FAQ-PS3.html]Folding@Home Project[/URL]
[*][URL=http://www.funforourtroops.org/]Fun For Our Troops[/URL]
[*][URL=http://www.gaming4others.org/about.htm]Gaming4others[/URL]
[*][URL=http://www.get-well-gamers.org/]Get Well Gamers Foundation[/URL]
[*][URL=http://www.giftsfromgamers.org/]Gifts From Gamers[/URL]
[*][URL=http://www.gamersoutreach.org/]Gamers Outreach Foundation[/URL]
[/LIST]
We'll leave it to them to introduce themselves. :)