Be the match!
The National Bone Marrow Donor Program, also known as Be The Match, describes their cause thusly (from their website): "We help patients afford transplant, find a matching donor and build a future as we advance medical research." You can actually take the first steps to joining the registry as a potential donor online.
Event: It's quite simple: you provide the relevant medical information they need to make sure you qualify to be a bone marrow donor, and if you do, they send you a kit in the mail for swabbing cheek cells. You follow the instructions in the kit and send it back. Having done this, I should be in the registry within five to six weeks. Once I'm listed, if I appear to be a match for someone in need of a transplant, I will go in for more tests to make certain. Once it's proven that I'm a match, I'll make the donation.
Reactions: Well, clearly there haven't been any yet from those directly affected, as I've only just signed up; however, I would like to mention that I find it kind of funny (also a little frightening) that everyone I've told thus far has seen fit to make certain I know how much this is supposed to hurt. Yes, I know. Thank you for reminding me.
Would I do it again? Ah, well, that's not really an option. I'd totally sign up to be an organ donor or to donate blood. Same thing? Sort of?
Effort: It certainly wasn't taxing.
Time: I'd say, all told, about an hour.