Today I learned about donating bone marrow.
To be put on the donor list, all you have to do is fill in a form and spit. Literally. They just need a spit sample to be able to match you to a cancer patient who desperately needs your stem cells. Then they take out your bones and scrape them out... NO THEY DON'T!! They just extract the cells from your blood, or (in some cases) your hip bone, under anesthetic, and you'll recover in 48 hours or less. And someone else might NOT DIE.
It's not like donating blood where you go and donate and they store it in case they need it - you can keep all your precious stem cells inside yourself until someone needs them. Possibly someone who isn't a match with anyone else on the whole list.
All you have to do is fill in a form, spit in the post, and keep your address updated on the list just in case you are a match for someone one day. No holes will be made into you for any other reason than attempting to save a particular life, and even then: only very small holes.
I didn't know that.
Anyway, here's how to sign up.