I love this combination:
1- the Octovo Solis Light:
http://www.octovo.com/product.aspx?cid=72&pid=24
2- this m-edge cover:
http://www.medgestore.com/products/kindle3-latitude.psp
I like a zippered cover, and it's one of the lightest covers I've found with a zipper. The light takes a AA battery. I like the light very much; I had it for my K2. I had tried one of those gooseneck type lights, and found it mildly annoying to adjust it. The solis is perfect, and small and easy to transport.