Flickr has launched a service called "The Commons", which will allow users to help describe pre-existing reference collections by adding tags to them. The program was established in collaboration with its first participant, the U.S. Library of Congress. Fast Facts:

1. Pilot program initiated in July 2007
2. Only includes the Library of Congress collection (as of Feb. '08)
3. The Library of Congress images are considered to have "no known copyright restrictions," which Flickr hopes other similar institutions will adopt for their content once the Commons project catches on