For the camera buffs:
- Gustavson, Todd. Camera: A History of Photography from Daguerreotype to Digital. Sterling Innovations. 2009. 368p.
For camera lovers, this is perhaps the best history of picture-taking devices. Made in collaboration with the George Eastman House, this book distinguishes itself from the other "1000 cameras" books from its rigour (nobody calls it 120mm !), its depth and its breadth. Too often books on collections of cameras are biased toward a particular collector's quirks, or suffer from incorrect fact-checking, fanboyishness, and lack of historical connexions. This book is free from those defects, and articulates clearly the links between the various models and styles.
- McKeown, James M. and Joan McKeown. McKeown's Price Guide to Antique and Classic Cameras. Centennial Photo Service. 2004. 1248 pages.
Powerfully exhaustive list of an incredible amount of cameras from the 19th century onward. Authoritative, big, and heavy. Worth checking to see if you have all the models in your collection or to discover new gear to lust for.
- Stafford, Simon et al. The New Nikon Compendium: Cameras, Lenses & Accessories since 1917. Lark Books : 2004. 416 pages.
Catalog of every lens, camera, viewfinder, accessory, cable release, finder, etc produced by Nippon Kogaku since its inception.
There are plenty of compendia for other camera makers (Zeiss Ikon, Rollei, Leica, Canon, etc), but I don't know them all since I'm not really of a collector. Many are labours of love, printed on small presses, but they also tend to be the only things available since the makers themselves do not so religiously compile their own data.