The Photobook Vols. I & II by Martin Parr and Gerry Badger. These two books are a must for any photography book compulsive
Vol I came out a couple of years or so ago, Vol II came out last year (there may be more to come?)
Each takes a thematic but eclectic survey across the history of the photo book
The are some fairly obvious choices listed - The Decisive Moment, American Photographs, The Americans (and in volume II, books by Shore, Gursky, the Bechers) But there are also some listed and described which may send you scurrying to http://www.abebooks.com/ , as well as some books you would probably never imagine had ever been printed and published - e.g. 10 Years of Uzbekistan, The Book of Bread and Waterfall Rapture - Postcards of Falling Water: My Addiction My Collection.
Though I must say one unfortunate side effect of the two volumes has been to drive up the price of certain books, especially those long out of print. Try finding a decent priced copy of the brilliant (but at one time "just another" aperture monograph) The Pond by John Gossage. In fact, try finding a copy at all now.