EdWeb.net is a relatively new social networking site similar to Ning, but dedicated solely to education. It also has a LOT fewer people on it, which can be good or bad depending on your point of view.
I loved Ning when I first joined a few summers back and everyone was discovering the joys of professional social networking. However, it has grown a bit ponderous and unwieldy for me, so I haven't been on in a while.]
EdWeb offers several features: blogging, chatting, calendar sharing, a wiki, document archives and more; I like the interface better than Ning--it seems cleaner and easier to navigate. Of course, there aren't many people with which to form a network yet, which is a drawback. But there is a school librarians group with 50 members in it; it will be interesting to see if we can make that a viable community.
I am a bit concerned that there already seems to be a corporate presence on the site. Again, we'll see what happens.