Compare to kidney exchange (http://transplants.ucla.edu/site.cfm?id=112): if your friend or spouse needs one, but you're incompatible, you can find another pair who has the inverse compatibility problem and swap with them. Or more, and form a chain (e.g. this 35-kidney chain: http://abc27.com/2015/03/30/paired-exchange-record-70-people...).

What I was referring to is Good Samaritan donation:

Many Good Samaritan donors choose to start chains because it is a way to help more than one person suffering from kidney failure. One chain typically facilitates anywhere from 2 to 30 transplants. The NKR pays for donation insurance for all Good Samaritan donor who start chains through NKR.

http://www.kidneyregistry.org/living_donors.php?cookie=1

EDIT: Ah, found it---they're called Kidney Vouchers :) http://transplants.ucla.edu/site.cfm?id=406 great name. Although limited to one predetermined person, so not exactly a blanket "+1".

Still, all of those things are excellent ideas.