In a similar move to harness the public’s knowledge about old photographs, the Library of Congress a year ago began adding photographs with no known restrictions to a Flickr service called the Commons. The Library of Congress started with 3,500 photos and adds 50 a week.
The project relies on Flickr’s ability to allow users to leave comments, below the picture or even within the picture to fill in the blanks. In a report assessing the project (conclusion: it has been a huge success) the library detailed the information that had been gleaned from Flickr users.
Full story in the New York Times