Japanese researchers have successfully found a way to wirelessly transmit electricity through concrete. Granted, it’s not a lot of current, about enough to run a light bulb through about four inches of concrete, but the potential applications could be endless.
The article linked above speculates on using electricity like this to power electric cars. Highly unlikely, given the enormous amounts of power these vehicles require. But if a road surface could conduct electricity you could use that capability to power street signs and lights and monitor driving speeds and traffic density, for starters. Any other ideas out there?