The National Archives has established a YouTube Channel. If you enjoy getting lured into the videos of YouTube as I do, you will love the new National Archives offering that will, I am sure, take up hours of your time.
An old saw is that to be a good genealogist you need to be a good historian. This site will help you with both of those. It offers captivating videos from presidential libraries, the space race, WWI & II, to mention only a few.
Check it out at: http://www.youtube.com/usnationalarchives