This is cool: WIRED lists five iPhone apps that replace bike hardware. I think the most clever is a Cyclocomputer that measures your bike's speed by counting the sound of a plastic tab on the spokes. Another clever app is a brake light that uses the built in accelerometer.
Darcy Darlin' asked what kind of helmet is on Heinrich Haussler's head. That would be a Catlike helmet, which is not legally available for sale in the USA (it's not CPSC approved) although I know people who import it anyway.