Ning is a social networking site or 'A Viral Expansion Loop' as it is popularly know in Silicon Valley.

Ning allows users to create their own, custom, social networking site including customized web pages for profile pages. Originally built on n open source, Ning is a competitor to MySpace and Facebook.

Ning is different from Facebook and My Space in that a user can start his or her own custom social group, catering to a specific audience or topic making it attractive for educators. Basic, advertisement-carried Ning-accounts are free. According to Wikipedia, Ning hosts more than 500.000 networks.

Use in classroom
Since the Ning network allows for a more customized setting than Facebook or MySpace it could serve well as class room bulletin board. Individual students can create their own pages/profiled. Announcement and events/calendar can be posted, photos can be uploaded and organized into albums, video can be uoloaded and shared, and widgets can be incorporated that allow integration of photos, video, and music on Ning to be shared on Facebook. Further, discussion forums allow students to interact on topics and express their point of view on any given topic.