When I introduce teachers to Web 2.0 in a professional development event, I urge them to join Classroom 2.0. When I read Peggy George's request to submit a list of Top Ten new ideas, techniques, tools, books, conversations that made 2008 special for you for the "What We Learned in 2008." show on January 2, 2009, it gave me the idea to create a list of reasons why teachers new to Web 2.0 or Social Networking should join.