In their own words ‘Psych Central is the Internet’s largest and oldest independent mental health social network’. From what I can find, it seems to be true. They have been online since 1995, and last year got close to half a million unique visitors.
So consider it as the social network that started before the age of social networking. It now offers blogs, forums, reviews, news, feeds, tweets and other community features to people interested in mental health. Seems like they are making a decent revenue with it too.
Always good to see focused, pragmatic and simple solutions being successful. Proves the point that social networking has more potential when done in a niche way.

Medpedia is an attempt to apply crowdsourcing concept to medical knowledge, just like Wikipedia. It launched in beta mid-February this year, with some 