clever Stanford techies from Boston hack it with the Axe :-). I recommend implementing this not from scratch as you are trying to, but rather as a mod for the phpBB forum. This will basically save you a great deal of work since the forum already does most of the things you expect in this sort of marketplace, provides you a great admin panel and has no bugs (not like what you may end up getting elsewhere). We would just add some private communication channels, personal control panel associated with projects, nice searchable profiles, and voila. "The Russians used a pencil". Price is negotiable.