There is a product called the Walit, however, this guy was completely disappointed. The Walit was terrible. It was dim, the batteries took up too much space, and it had a flimsy clip to turn the light on and off. The very next week, this guy published an ironically scathing review and presented his solution - Walluminate, on the Bleeding Edge, a weekly video show, which you can view below:

More details about parts used to create the Walluminate.