http://education.skype.com/

Skype in education is free and a great way to collaborate, communicate, and connect with other teachers, classes, authors, doctors, professors, musicians, and other professionals from across the country. What a great way to connect with someone from the country you are learning about in social studies, or chat with the author of the book your class is reading, or the possibilities are endless.

Here is a link to a post with 50 ways to use Skype in the classroom.
http://edudemic.com/2012/08/skype-in-classroom/