I think generally these type of shots are referred to as "setup shots" or "behind the scenes" rather than backstage. Why exactly are you looking for them?
If you're looking for inspiration for DIY and amateur set ups I would add the following group to chills' list:
Which contains both the set up and the final shot which is quite helpful for working out how things are done.
If you're looking for something more "pro" then several photographers who are active on the net post really good behind the scenes videos, try:
The F-Stop also regularly features set up shots and original images that are composited together, along with in depth interviews with the photographers/artists involved:
A great source, though not so very webby, is the series of articles Monte Zucker did for Shutterbug magazine over a number of years (certainly throughout the late '80s and '90s). There was rather a lot of detail about the setup, the whys and wherefores (complexion, clothing, tonal range, location constraints, that sort of thing). You may be able to find them archived in a local library, or if you know anyone who's been a shutterbug for a long enough time, they're likely to have something lying around.