The Wiki Way
WikiWiki (which means "fast" in Hawaiian) is a lightweight Web collaboration system originally designed by Ward Cunningham for his Portland Pattern Repository. Wiki turns conventional collaborative software design on its head; it offers no security, little or no formal organization, no metadata, and no support for presence.
It's been remarkable successful, because its weaknesses become strengths. Since the system is so clearly insecure, users take special care to protect it from vandals and casual neglect, Since the system is so informal, incremental refinement becomes an explicit virtue. And since there's so little overhead for security, authentication, transactional integrity, or synchronization, the system is very small, very simple, and very fast.
An interesting aspect of this book is that much of it encourages the reader to hack the system's source code. The code is supplied on a CD and may be downloaded from the book's support Web site, and provides a simple, flexible PERL system that I was able to bring up on MacOS X in a short evening of work. Rewriting the code is an interesting take on the old goal of the reconstructible user interface, but perhaps this is the way the future looks.