One of the most valuable books I currently have in my library is Magnum Contact Sheets. It is a book that was put out by Thames and Hudson in the last year or so, and contains over 139 contact sheets from 69 Magnum Photographers.
Admittedly, it's easy to sit back and take our digital cameras for granted. They are easy to use, fast, and convenient. Then you come across something that makes you remember just how easy it we have it sometimes.