LearnZillion -LearnZillion.com offers a free and growing set of Math and English Language resources for grades 2-12 that have been developed by expert teachers directly from the Common Core State Standards.
WatchKnow—as in, “You watch, you know”—is a nonprofit online community that encourages everyone to collect, create and share free, innovative, educational videos.
Open Culture: The best cultural and educational media on the web- usually a new interesting video each day.
Earth Explorer: AMAZING videos about animals on our planet. Great resource!
explore.org has recently launched a set of lesson plans which are written for the K-12 classroom, and fulfill grade level national standards. The plans accompany explore's films, which document people who have made a difference around the world.
National Archives Digital Vaults Project
..."browse through the hundreds of photographs, documents, and film clips and discover the connection between some of the National Archives' most treasured records." This Flash-based site (also available in HTML) allows you to collect assets, track your path, search, and create a poster, movie, or your own pathway.
MovieClips has thousands of short video clips from moviesWhat makes it a real winner is that that clips are categorized by theme, character, setting, mood, and more. They’re incredibly detailed.