Funny I should run across this thread today. Over the weekend, I found a pack of bandaids at the pharmacy that included a kit for sending in a sample of your blood (when you've cut yourself anyway) to see if you might be a match for someone for a bone marrow donor.
I'd never considered, but I think if I was a match to someone, I'd definitely donate. So, hit up your local walgreens/cvs. they're only like $3, or mine was on sale for 99 cents.