Ask questions to engage your students in authentic learning. Tom Barrett did this when his class studied probability by asking about the weather in various locations.
Communicate with other classrooms. The Global Read Aloud, Global Classroom Project and Physics of the Future are three examples of how teachers use social media to connect their students as they collaborate and communicate.
Create projects with other teachers. (Full disclosure: I co-created Physics of the Future with Aaron Maurer, a fellow educator I first met on Twitter.)
Share your learning with the world. My students are creating an Encyclopedia of Learning Games with Dr. Lee Graham's grad students at the University of Alaska Southeast. The educators are testing the games, and the students are testing them, too.
Further a cause that you care about. Mrs. Stadler's classes are working to save the rhinos in South Africa, and Angela Maiers has thousands of kids choosing to matter.