A network of plastic tubes, with blown air assisting cyclists in their direction of travel.
That sounds like a whole lot of fun, in a Futurama kind of way. I'd be there, for sure. Tom Turner says a similar idea has been proposed for Toronto. Wonderful notion, [crap web site]
(http://www.velo-city.ca/MainFrameset.html. But then, they probably have other things to be getting on with.