DARPA's robotic arm is legendary. It's the result of years of work and a whopping $100 million, but it just might be worth it: This arm mimics the natural motion of the arm, elbow, wrist, and hand with 27 different movements (including rotation, bending, and extension) that's at the top of the field. But what's really notable about this particular arm is how it's controlled: DARPA wants to implant a small chip in the brain that would sense and measure the firing of neurons, then convey those commands to the arm, all near-instantaneously.
Basically, this is a mind-controlled robotic arm. It's the followup to the "Luke" arm, the prosthesis developed by Dean Kamen (perhaps best known as the inventor of the Segway), but its thought-control system is far beyond the Luke arm's foot-pedal control. If I was going to rebuild myself, I'd want the natural control of my meaty "birth arm" with the added bonus of superhuman cyborg strength--so thought-controlled arms are a must.
Current status: Last we heard, back in February, the FDA was fast-tracking the project. That could knock years off the development cycle, but we're still an estimated four or five years away from actually using this amazing arm.
Runners-Up: The Luke arm