I was always losing those lights you clip on to your bike, and they’re not cheap or good quality. I had wanted to play with conductive paint for some time, so I purchased some in order to attach safety LEDs right to my bike helmet. I have made a page on Instructables detailing its construction. Here’s a nice picture, however, which is a link to the Flickr set. You can also view the circuit schematic.

Files:
LEDBikeHelmet_schematic.ai
LEDBikeHelmet_schematic.png