What new online communites does the world need?

Philip Greenspun's thinks some of his friends have more money than sense. These people asked him " What new online communites does the world need?". The comment that stands out for me is "MIT and many other universities have been making content freely availble via OCW. But having the content available is generally not sufficient for learning, for most people learning is a social activity". Learning's an activity you can't transfer to an online only context - social networking probably isn't suitable either. I mean, if you really wanted to work with someone would you really use LinkedIn?