DaveWiner's new project, a web of interlinked outlines, which can be updated by anyone and expanded in place. :
world outline : http://archive.scripting.com/search/default?q=world+outline
works well for small groups. Compare CreativeNetwork
** likes Winers vision but not format : http://dannyayers.com/archives/2005/07/14/xoxo-template-for-blogs/
** My hunch. Vision is more important than format. But compelling application beats both.