When I think about it, fingernails would be an ideal place to have data – it is a relatively flat place on the body, it is a rigid location which could hold the information without fear of flexing, and you do usually have 10 of them for multiple display locations. But is it practical?
Timex and Core77 held a global design competition called "2154: The Future of Time Design", and the TX54 concept was an entry. What is the TX54? It is an ultra thin disposable clock and calendar designed to be wore on the thumbnail. If it is dark when you need to see the time, simply press on the edge of the thumbnail for back lighting.
Now if only they had other informational displays for the other fingers.
