Great short easily digestable film clips, documents, and challenges that follow the standards fairly closely. Both regular and AP versions of U.S. History - geared toward high school but I use these clips regularly with my 8th grade class. They tend to retain information from the clips much better than information fron their text (TCI).
These fellows presented their online study resource - which includes, introductions, lesson plans, timelines, fun facts, summaries and test reviews, and a large image gallery sorted by time period - at a conference I attended in Pasadena last Spring. I think it is better for High School teachers and students. I teach 8th grade and use it mostly for my own edification.