Through the Viewfinder photography is defined as taking a picture of any subject through the viewfinder of any camera with another camera.
A year in the making. This is the first volume of what will hopefully be many TtV photography books. This book was created out of the group of TtV photographers on flickr, it is filled with their collective submissions and personal favorites. This book really covers a good range of what has been done with the format and still leaves you wanting more.
you can learn and view more here