Yahoo! Answers. Monumentally popular, enormous traffic, and containing absolutely no useful information, Yahoo! Answers is actually more of a teenage chat room than a place to get real answers.They also highlight failed attempts to bring the Ubuntu and Unix community sites together to make a single community. The process of defining a "topical community" reminds me of the problems we have in IR when we define a "topic based vertical" to apply domain knowledge in retrieval. From their blog:
Communities consist of concentric circles. You share more with people in the inner circle than you do with people in the outer circles, but if you were in a strange place, you’d seek out people even from the larger circles. If you’re building a community (or a Stack Exchange site), it’s not immediately obvious which level is going to work...They are developing rules that use the size and degree of overlap between communities to guide the process. It will be interesting how this plays out and what lessons we can use to apply to IR.