[Tom] sent us a link to this very professionally done project. He built a bike light that is a 540 lumen Luxeon light with a custom case. The LED, Lens, and driver were purchased first. Everything else was designed around it. The design is compact and good looking. You can download the CAD files on the site if you want to make your own. He is using an Atmel AVR ATTiny13 to control brightness.