Social media is not about the exploitation of technology but service to community.
AFT's Share My Lesson hosts an impressive searchable bank of lesson plans and associated documents and files (currently 293,007). The lessons are rated by users and comments can be left about the lesson and its implementation. There is a community aspect which allows users to follow other users and participate in forums as well as a section dedicated to Common Core implementation with standards aligned resources. It's a "by teachers, for teachers" type of service and it's definitely worth checking out. You can learn more by watching the video below or clicking on the logo to go directly to the site.