Although this tread is old it has a lot of good info about reading lights. That's the reason I want to share with you my expereience with the just received the Belkin Clip-On Reading light for Kindle, which fits perfect on my Sony reader. Picture on:
http://www.gadgetreview.com/2010/05/...ing-light.html
It has 3 LED's and 3 AAA batteries is light and spreadout the light very well. This makes it possible to avoid reflections.