+1 on the organ donor - It is a good thing to do anyway. My instructions are to recycle everything possible when I am through with my body.

We seem to be talking about somewhat different contacts. There is the legal version, Medical Power of Attorney, Estate Trustee, who can make crucial decisions on your behalf, and the expedient version - someone who knows something about you and can provide information about you if you are unable to communicate. Nothing worse than trying to render aid to a mute body with no significant information - no history, no symptoms, no feedback.