A kid I went to high school with created this company Biyo[1] that plans to extend their service to many different fields, including medical, for purposes like this. You no longer will have to fill out medical forms when going to different doctors, no more dropping off cd's or usb's of xrays or other tests to other doctors. I can definitely see this getting to the point where you don't even have to go to the doctors to get access to your medical information. These devices can be placed around town to use like ATMs,and can even replace an ATM.

Your signature would also be nearly impossible to fake, and somebody can't just cut off your hand to impersonate you because that would destroy the signature as well.

[1] http://biyowallet.com