The Teacher Experience Exchange is a social network designed by HP for educators. This is a nice site for finding educational resources such as web 2.0 tools and lesson plans, and of course collaborating w/ others. Also, this is a good site for professional development and articles are rated on a 5 star scale which helps for deciding on what is relevant material.
I recommend checking out The Teacher Experience Exchange by clicking here!!
For my top 20 social networks for education click here.