Graham Clarkes the photograph - A visual and cultural history. He examines the main subject areas in photography; landscape, portraiture, the city, the body and reportage.
Camera Lucida Roland Barthes - This ones pretty heavy but is worth the read. Rolands reflections on photography and how he observes subjects in front of the camera.
Liz Wells' Photography a critical introduction - Photographic theory great for those studying photography and a must read for university level students or those going onto university.
Susan Sontag on photography - "A brilliant analysis of the profound changes photographic images have made in our way of looking at the world and at ourselves over the last 140
years."—"Washington Post Book World"
Ways of seeing John Berger - This challenges how we look at works of art and the way in which we perceive our environments.
The Photographer's Eye: Composition and Design for Better Digital Photos Michael Freeman - This is about ideas, examples, theory and lessons in photography and is a very good book to help you understand why you are taking a photograph and the best way to photograph your subjects.
The Photographer's Mind: Creative Thinking for Better
Digital Photos, Michael Freeman - He looks at what makes a photograph great and explores the ways that top photographers achieve this goal time and time again in regards to composition, avoiding cliches and much more.
These books are so interesting if you want to know more about photography and can all be found on amazon.