I just went w/ the "Kindle" branded Mighty Bright XtraFlex2 Book Light......yeah, it's a little big for the Kindle 3, but my major concern was 1) good leds/reflector, 2) goose neck, and 3) AA or AAA batteries (w/ the option for an adapter).
It is doable on a Kindle 3, at least for me, and especially for reading in bed. It was definitely "not" precision made for the Kindle 3 though.
My 2C.

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