I live in a one bedroom apartment, but I have six seven foot tall bookcases completely filled with books. I have far more history and literature than photography, but I have a good amount on the subject. Not to get too much like a library, but my major foci:
Literature: Nabokov, Salinger, Fitzgerald, Pushkin, 19th century Russian poetry and literature.
History -- Russian-Japanese relations (my graduate work). Russo-Japanese War; late Tokugawa and Meiji Japan, Imperial Russia, Sino-Japanese Relations, German and Italian unifications, origins of World War I. Japanese pop culture, Thucydides, Livy.
Music: Shostakovich's life and politics (my undergraduate work), Bach's secular works.
Photography: Ansel Adams: The Camera, Negative and Print. Japanese Photographers -- Eikoh Hosoe, Tomio Seike, Shomei Tomatsu. HCB, Martine Franck, MoMA history of photography (1960s), Aperture Past Forward, Julien Busselle: Printing and Processing. Beyond Basic Photography, Advanced Photography, The Manual of Photography, The Film Developing Cookbook.
Anyway, all that with a bunch more general history, art, architecture, Russian and Japanese dictionaries, literature and so forth. I just accumulate books like I do camera gear...I would estimate that I have over a 1000 books so far, and I am not yet 27...