Well, although the book is very detailed, not exactly everything is covered. Setting up some of the newer frontends and whatnot comes to mind. The book would be of no help there. Or all of the new goodies coming to life with the Led Wiz. There are several thing I could think of that wouldn't be in the book.
Having an entire forum dedicated to tutorials? I don't know about that. Maybe section specific tutorials would be good as sticky threads, like the powerstrip writeup.
While we are on the subject of tutorials... I think it would great if people started throwing some video tutorials up on youtube. Video tutorials are much better IMO. Those could be stickied. Anyway, those are my thoughts.