The Library of Congress in cooperation with UNESCO launched the World Digital Library today which gives electronic access to a number of early primary documents in the form of photographs, papers and from archives in various countries around the globe. The World Digital Library is available in seven languages.
The Library of Congress is an amazing resource for documents and photographs from the United States available at its Digital Collections and Services. Last year, it created a pilot account with flickr of one collection and 6 sets.
The image below is a mosaic made from civil war photos.