Russian designer Anton Guglia has created a bookmark that uses LED lighting technology. The 'Bookmarklamp' turns off when the book is closed and turns on when it is open. Just place the bookmark between the last page and cover, switch it on and bend it however you see fit.
The battery-powered light illuminates one page of your book at a time, which I suppose could be a bit of a hassle, especially if you have to keep switching the bookmark every page or so.
The Bookmarklamp's wide surface area is an ideal spot for a logo, which offers a great promotional opportunity for bookstores, publishing companies and ad agencies.