I was surfing around this morning and ran across a delighful series of articles on architectural photography at about.com . These articles give interesting background and history to the subject of photographing buildings as well as and links to work by some of the greats in this field link Ezra Stoller and Julius Schulman.
Even though Architectural Photography is not the same business as Real Estate photography there is overlap. For example there is passage in the history section of this article that describes that at the turn of the century Architectual Photographers would use a plumb line to make sure their camera backs were parallel to the plane of the building being photographed so the verticals would not converge. Modern RE photographers fight the same problem but use faster, easier techniques.
There are links to a number of case studies by some of the big name architectural photographers I think you will find interesting.