At our local Meijer I picked up a Universal Q-Lite BBQ grill light for $8.00 on clearance. I noticed that the clamp looked like it could fit around a bike frame, and it does nicely without marring the surface. It's a little weird at first because I'm used to having lights on the bars, following where I'm turning. Because I have it on the front of the frame, it's sluggish to follow. Thankfully it is bright enough not to worry about it. The light swivels all over the place, so I could put it almost anywhere.
This is the only image I could find of it online:
I looked for something like this because I wrapped my bars in Bontrager padded gel tape, and didn't leave any room for bar accessories. Oops. :)