Skype in the classroom
How to get started: http://education.skype.com/about
"Skype in the classroom was created in response to – and in consultation with – the growing number of teachers using Skype to help their students learn. It's designed to help like-minded teachers find each other, collaborate on projects and share inspiration and resources. Browse all of the projects on Skype in the classroom. (Each project sets out what kind of help is needed.)"