I've always been interested in prosthetic limbs and such, and Dean does a nice one about the Luke arm, here:
http://www.ted.com/talks/dean_kamen_...prosthetic_arm
I have two favorites, kinda, I really enjoy this one which discusses TED talks (so meta)
https://www.youtube.com/watch?v=Yo5cKRmJaf0 but this is another amazing one on bionics that I promise if you watch til the end will be so gratifying:
https://www.ted.com/talks/hugh_herr_...mb_an d_dance