Well, I’ve heard of book lights, but the Flylight is the first light I’ve seen made specifically for your laptop. The flexible bendable Flylight is a small light put out by Kensington that is powered by the USB port of your laptop.
Michael Mardings of TheCelebrityCafe.com mentions the Flylight along with several other Kensington products in Kensington Laptop Accessories.
It’s available for less than $20 from Amazon: