I have been a long term fan of Seth Godin new media marketing guru who has just released a new book called "Tribes". Tribes is an insightful discussion on how groups are formed and how they are led and why new social software is making them more common and incredibly successful.
I highly recommend Tribes to you as an insight into how groups are formed and function based on the leadership they are given.
Seth Godin's Blog
Seth Godin's website
A free audible downloadable copy of this book is available for a short period from the Audible Website
