This is the first book mark that I’ve seen that doubles as a “flashlight”. It’s the Book Mark Light from the Design Bloom Shop. The book mark is actually a circuit board that has been printed on a thin film with special conductive ink.
The Book Mark Light performs like a traditional book mark to save your page, but when you sandwich a CR2032 lithium coin cell battery between both ends, it lights up.
You can read more about the Book Mark Light and order one for $16 from designbloom.com