Web-based tools continue to proliferate, giving teachers more to add to their arsenal, but it can be hard to determine which resources are worth spending time exploring. Here is a list of interesting tools curated by Adam Bellow, founder of EduClipper, and Steve Dembo, Online Community Manager for Discovery Education.
http://blogs.kqed.org/mindshift/2013/07/13-free-web-tools-students-and-teachers-should-know-about/