Everybody knows about the concept of replacing parts of the human body for mechanical ones from scifi-movies. These techniques may however be closer to publical release than you think.
Dean Kamen, inventor of the segway, has been working on a prosthetic arm for some time. The arm is special in that it is controlled with the same nerves that a normal arm is “controlled” with. This is done by relocating nerves from the original arm to the breast muscle of a patient thus giving the patient the ability to control this muscle via the same “inputs” as had it been the arm. Sensors are then connected to this muscle, and these sensors are connected to the robotic arm.
It is easy to find out more about on the web.