Howard Reingold's book with the string "Virtual Community" in it. Old though: 1994 or so, but very informative on pre-Internet communities. The chapter on France's Minitel (term?) I found particularly valuable.

I've been participating in online communities since 1992, and most of my information has come from short comments by people trying to preserve the character of specific communities. Paul Graham's comments on Hacker News are particularly worthwhile, but have not been collected in any one place.