Innovation, collaboration, and creativity are important components of 21st century learning. There are tons of websites (that are free!) that teachers can incorporate into their classroom.
I came across another list of websites posted by the American Association of School Librarians that should be checked out (no pun intended)! This post categorizes the websites by "Media Sharing", "Digital Storytelling", "Manage and Organize", "Social Networking and Communication", "Curriculum Sharing", "Content Resources: Lesson Plans and More", and "Content Collaboration". Even though these lists are in the 2010 tab, the sites are still spectacular for 2011-2012.