Every time you contract a muscle, it emits a little electricity that you can record with antennae or electrodes and use that to operate the motorized prosthesis.

And this article from The Economist summed it up beautifully about the opportunities in health across the developing world Mobile phones made a bigger difference to the lives of more people, more quickly, than any previous technology.

So if we're not worrying about directing traffic, if we've transcended paper, if we are worrying less about control and more about description, then we can think of the English language as being this beautiful mobile.