After extensive searching, I believe that I have the majority of the international book publishers who have a strong interest, if not an outright focus, on photographic monographs books linked up on the sidebar. These are the publishers who are printing the interesting photographic projects, sometimes in very limited production runs which can be very beautiful and very collectible books. They are the ones who also take more risks on photographers who are not as established yet.
I have purposefully not listed the really big publishers, for whom the photographic book market is but a small segment that they publish. The mammoth publishers are more risk adverse and make the big print runs of very established photographs or generic photographic themes. I have not listed a couple of smaller publishers who are providing only technical or how-to photographic titles.
If I have missed any, please let me know.
Best regards, Douglas Stockdale
Update: Since I started this list, I have found some very interesting titles being published by some of larger publishing houses, thus I realize that my earlier assessment was not entirely accurate, so the listing and links has become much broader. I still realize that I have a weakness in my links for the non-USA photobook publishers in Europe, South America and Asia, particularly Japan & China. So I will be adding these publishers as I become aware of them.
PhotoBook Journal 
I visit every day some websites and blogs to read articles,
however ths web site provides feature based writing.