I bought one of these last year:
http://www.amazon.com/gp/product/B00...ilpage_o04_s01
The light is nice and bright, but the mount is pretty crappy. I made my own, but then the wiring started getting flaky. I works, but I have to twist the connector around to get it to stay on.
Earlier this spring, I bought a Cygolite Streak 310, and love it! Awesome mount, not as bright as the other, but enough to help me dodge potholes at 30+ MPH in the dark. USB rechargeable is nice, too.
Amazon.com: Cygolite Streak 310 USB Light