Discussion Groups and Forums
LinkedIn Groups
Communities created by LinkedIn users for people with a shared interest or cause.
Yahoo!Answers
A forum where Yahoo users can interact with each other by asking and answering questions.
Google Groups
A collection of communities where Google users can interact with people who have similar interests.
Tangler
A host site for a large collection of forums.
Blogged
A community of people who interact around an aggregation of blog posts discussing the most recent news.
MyBlogLog
A social networking site for bloggers.
Bzzscapes
Community of users who share content and discuss their favorite brands.
GetSatisfaction
Community of consumers and companies interacting and answering each other's questions.
Gather
A community of people looking to interact with people they haven't met before but who have shared interests.