Of the Nings, I really liked TeacherLingo. It offers everything from Interactive Whiteboard resources to lesson plans and even fashion advice specifically for teachers. I think this is a great way for teachers and librarians to stay in touch, collaborate, support each other, and build networks.
When I looked at the Texas School Librarian Ning I discovered that our class mate Erica Finley is already a member. Now the rest of us just need to follow her lead.