Here's another great list. This one was was sent to me by the folks at onlinecollegecourses.com: http://www.onlinecollegecourses.com/2012/08/20/25-tools-that-take-tutoring-to-a-new-level/
From the article:
"Like other areas of education, tutoring has seen some radical changes in the past decade courtesy of new and increasingly innovative technologies. Students and their tutors can now interact at any time and from anywhere in the world, and tutors can create and share educational resources with their students in minutes using high-quality and often low-cost online tools. Learn more about some of the websites and resources that are helping to define the new face of tutoring by reading about a few of the best of these new tools that we've collected here."