Shout Out - Why do you love Classroom 2.0?

I'm presenting on Web 2.0 tools to 90 teachers on November 19th in Ottawa. If you could reply to this discussion with where you teach and why you find Classroom 2.0--or Nings in general--so useful, it would help me demonstrate to them the power of social networking. I guess this is the Ning equivalent of a Twitter shout out. Thanks for your help, folks.