Google has joined forces with LIFE Magazine to scan and make available millions of Life photos from the 1750s to today! They have some fun photos on the main page (images of Queen Victoria, Walt Disney, Charles Lindbergh, the American Civil War, etc). Check it out at http://images.google.com/hosted/life
One cool photo in their archive: WWI flying ace Baron von Richthofen with his triplane from 1917.
This image was found at http://images.google.com/hosted/life/l?imgurl=0de7404c72ac508d&q=Baron+von+Richthofen+source:life&usg=__MoRTjZUctp4gIvUscUyjX5I9Lbc=&prev=/images%3Fq%3DBaron%2Bvon%2BRichthofen%2Bsource:life%26hl%3Den%26sa%3DX