There’s a handy on-line tool for visually comparing camera sizes at camerasize.com. I’m not certain that the measurements are all correct, though. For example, the thicknesses of the Nikon D70S and Nikon D700 bodies are specified as listed on Nikon’s website—78 mm and 77 mm, respectively—but the visual comparison indicates that the D700 is thicker (including the pentaprism housing). This actually matches my impression of the cameras in real life (i.e., the D700 is larger all round, whether including the pentaprism or not). Checking just now, a D700 measured some 80 mm thick at the pentaprism, and around 60 mm at the lens mount. Exploring a bit more, I found that the D700 appears to be 77 mm thick at the hand grip.
The point of this is that you might want to check measurements in real life if you’re seriously considering acquiring one of the listed bodies. I suspect the measurements might be of limited value, particularly if different manufacturers specify the dimensions using different definitions (e.g., thickness at pentaprism, base of body, lens mount, or hand grip). Nonetheless, camerasize.com’s pictorial comparisons are interesting, and presumably mostly accurate, ones.