Urban Blight is an excellent sourcebook for city based encounters. Layout suffered a bit at times and editing needs some improvement, but the writing is good and some of the ideas are great. I like the criminal physician for example A little bit of a twist on 'em so he's not completely standard. Another good source of these things is the often talked about City Books by Flying Buffalo, supposedly still available from the source. Crisp writing, good art, and excellent maps. The only problem? Not D20. (Yet I'm hoping.) These books really are a classic of the fantasy campaign. There are some others I'll try to think about..