Isaac Salazar calls his works “book origami” and says
I see my work as a way to display a meaningful piece of art onto a book that would otherwise sit on a shelf and collect dust; it’s also my way of recycling a book that might otherwise end up in a landfill… If my work also makes people look at a book and even art in a new light then the piece has done its job.
You can see many more on his flickr page.