There's a new social networking system being created just for healthcare workers (read about it here) called GenCache.com that sounds pretty interesting. According to an e-mail I got from founder Jay Limaye, "You'll notice that in addition to the collaborative symptometer, we facilitate the means for users to contribute and create their information bank with articles, make announcements etc. Do take a look, you'll like it. We have a social networking model in the same mould as Friendster or LinkedIn but are totally focused on the healthcare space."
Feel free to go poke around--if this takes off, it could turn into something powerful.