It's got nothing on Dean Kamen's Luke arm, but YouTube user sumthinelse5790's utterly brilliant Lego prosthetic arm uses electric motors and extensive pneumatics to almost fully recreate the full range of motion of a real human arm, hand and fingers.
While it certainly comes in a far cry cheaper than Kamen's creation, the Lego prosthetic is unfortunately not a practical replacement for the real thing. Although it's adept at gripping and holding various objects, it's only strong enough to lift a kilo at most. And even sped up to twice the speed in parts of this video, it moves very, very slowly. Still, is there anything that can't be recreated with Lego? [YouTube via Make]