There are other donations that living donors make besides kidneys. People donate blood, plasma and bone marrow. I know people that donate blood and plasma on a routine basis and people who have donated one of their kidneys to family members but I have not yet met someone who donated one of their kidneys for purely altruistic purposes.
This article in the Globe and Mail makes one think about what would you do. I have filled out my donation card and carry it in my wallet outlining my wishes to donate whatever body parts are deemed worthy for transplant into others. If I was faced with the decision to donate a kidney or bone marrow to my DH or sibling, I could do it. I would want them to have a better life if they needed one of my two healthy kidneys or needed some of my bone marrow. But I could not donate one of my kidneys for purely altruistic reasons to an unknown stranger. It takes a special person to be willing to take that step. Lisa Sayer is a special person.