I'm actually doing this as well and was considering hitting up WF users for donations:
http://www.communityatcp.org/NETCOMMUNITY/Page.aspx?&pid=242&srcid=259&frtid=111
Basically, I run a marathon (26 miles!) to raise money for children with Ataxia-telangiectasia (a really messed up disease). I still haven't committed because I just started to train and I'm only up to 8 miles per session. However, I still have about three more months to train.
But if everyone were serious, I'd do it. I can run a marathon with a mustache as well.

Anything for the kids.