Another aspect that I think is interesting (and discussed in a few other threads) is this business of realism in pictures with or without vehicles and people. Here's a picture that I think most people would have a hard time believing this is in fact a diorama, or model, and again comes from the magnificent work of Chuck Doan.
(photo courtesy: Chuck Doan)
This, I believe, is his most recent build, which I hope you will visit here:
http://public.fotki.com/ChuckDoan/model_projects/untitled-half-inch-/