The ones I was really impressed by were ArtsEdge- which ties the arts into every subject area and is provided by the Kennedy Center. There was a terrific lesson on the Music Abraham Lincoln Loved. I also found ReadWriteThink. This is a great Language Arts resource. Many of us struggle to find many ways to keep the learning novel and new! This resource really helps teachers to find fun ways to help students strengthen their Language Arts skills. Another great piece I added to my teaching toolbox from this class is Edsitement. It was created through the National Endowment for the Humanities. There are lesson plans and other activities that teach about History and Art from grades K-12!
This was a really great chance to explore. I made a page on my website that talks more about these great tools and can be found here! I can't wait to borrow a class of students and try out some of these tools first hand!