Odd Bikes

Jeff Napier has a web site devoted to odd bikes. It's worth a look.

http://www.odd-bikes.com/

He doesn't have the Hula Bike (from bicycle forest) up there yet, though.
http://www.bikeforest.com/hulabike.php

That bike has no crank or chain. The rear wheel is eccentric, and the rider propels forward by bouncing up and down. They've got instructions up on the website.