I attended a great class this summer, on using Discovery Ed to support the common core. Discovery Ed has just started to add common core sample lessons on its site. To access this, log into Discovery Ed, then go to the "My DE Services" tab, and use the arrow to get to the drop down menu. Then click on "Streaming Plus" - this will take you to a menu tab that reads "Common Core in the Classroom". Right now, the sample lessons are mostly for Reading/Literature and Math, but we were told during the class that this is being worked on. I don't know if the link will work, but here it is: http://app.discoveryeducation.com/explore
Discovery Education also has sample lesson plans under the "Teacher Center" tab. I haven't used any yet, but I've been exploring more of the website this summer than I have previously.
In addition, since I teach History, I use a LOT of art and primary source documents in my lessons. I've found a great website that has many, many reproductions of great artwork in one place: www.artchive.com. It doesn't have all the works, but it truly has a sample of many, many artists, ranging from Medieval art to modern art.