Great list, and thanks for the link to our white paper on Communities of Purpose Rich - hope it proves useful :-)

Hi Richard I'm not sure I wholly agree with you there actually? I do take your point that people stay in comunitites of like-minded people, but there are a lot of causes (help, fund-raising, lobbying) which I think do give people enough bonds to stay together. See eModeration's white paper on the subject of Communitie of Purpose at http://www.emoderation.com/about/publications).