In the great pantheon of things unlikely to happen, this IBM idea ranks pretty highly, but that doesn't necessarily make it a bad one. Big Blue has applied for a patent covering a sophisticated new traffic lights system, which judges how long cars have to wait and sends them ominous-sounding "stop-engine notifications" when the pause is long enough to make switching off optimal. This is done by communicating with queuing vehicles and collecting their positional data, and subsequent start-engine notices are also distributed intelligently, as the first car in the queue gets it earlier than the second and so on right to the back. We don't know how many dudes would abide by the instructions of a lightbox up in the sky, but it's still a neat little concept -- maybe we'll see it in action when hovercars go mainstream.

[Thanks, Yuka]