How about this: Small cars that run on tracks around a city, automatically routing themselves direct to your destination. It's happening with ULTra, and it's being built in Cardiff. That's very cool.
I wrote at Upsideclown about this kind of thing a while back: Gifts, contracts, and whispers. And a post in my weblog too, about packet-switching transportation, based on the fact that we know loads about routing from the internet so why not apply that knowledge elsewhere?