I saw this on the White House Twitter: the National Archives photostream on Flickr.  The National Archives has uploaded some really interesting and incredible material to Flickr.  I am a history nerd, but look at all the finds:

• Abraham Lincoln’s signature on the last page of the Emancipation Proclamation;
• John Adams, Ben Franklin, and John Jay’s signatures (and wax seals) on the Treaty of Paris;
• George H. W. Bush, while Captain of Yale Baseball team, with Babe Ruth;
• an original photograph of the D-Day invasion;
• Flying School of the Negro Air Corps in Tuskegee;
• letter in cipher from a female Confederate spy;
• Albert Einstein’s declaration of intent to become an American citizen;
• and Maria von Trapp’s declaration of intent to become an American citizen (remember the Trapp Family Singers from The Sound of Music?).

And the best part is that most (if not all) of these documents are in the public domain, meaning you can reproduce them with no worry of copyright infringement.