Meter Runs Backward.

Short Popular Science article on a guy who puts power into the grid.

I so want to do this...

Update:

And this is cool, too. A related article about using cellulosic ethanol, a type of ethanol produced when the cellulose in plants (wood chips, corn cobs) is processed by termites into sugars and cooked up into go-juice, nicely saving the actual corn for cows, etc.