I find YouTube and Discovery Education most useful for social studies because these sites offer short and, often, creative videos that compliment the textbook.
Social Studies Music Videos
Copyright and Fair Use
I really liked the Fair(y) Use Tale. I did not know copyright protection could be enforced for a lifetime plus 70 years. Also, I was surprised to learn that "fair use" is not a right. It seems that "fair use" is to be used as a defense if educators are accused or sued for copyright infringement. Valuable information!
Dropbox could be used the classroom to foster student-student collaboration and student-teacher communication.