I still like Duane Michals' works. He uses photography not for documenting the reality, but for visualizing the concepts and ideas that he is obsessed with. Recently I searched for him on the net and found a few link to his works. See some of them here.
"How foolish of me to believe that it would be that easy. I had confused the appearances of trees and automobiles and people with reality itself, and believed that a photograph of these appearances to be a photograph of it. It is a melancholy truth that I will never be able to photograph it and can only fail. I am a reflection photographing other reflections within a reflection. To photograph reality is to photograph nothing."
-- Duane Michals
More links to his works:
1. One of my favourite 'sequences' by him.
3. The Essential Duane Michals