I would never sell my organs, but I'd gladly donate a kidney, part of my liver, a lung, or bone marrow to a family member in need.

I carry an organ donor card (marked "Any usable organs or tissues"), but recently I've looked into donating my whole body to the local medical college for research. If I do that, they can't remove any organs first, so I have to decide what's more important to me -- saving a limited number of lives immediately, or potentially saving many lives in the future through medical research.

And saving my family the cost of a funeral. ;-) The medical college pays for cremation and a container for the ashes when they're done using the body. Then they deliver the ashes to the designated next-of-kin.