What about if someone is practically dead because of a brain injury, he's already dead, but he can save someone else's life by donating his heart, kidneys, ....? I think this is very humane, I'd like to do that if I suffer from a brain death.
I also admire the people who donate one of thier kidneys to save a life, though I am not a kind of person to sacrifice that much for any person, though I'll do it for a member of my own family.