The Library of Congress has maded 2 of its collections of historical photographs available on Flickr. The goal is to get users to tag and comment on the photos, as well as help provide identifying information.

It's very interesting to see such a large and old institution embracing open social collaboration like this. When I was in school, the idea of user supplied freetagging was pretty seen as an edge-case activity even for things like private databases. This openness and the use of a site as simple flickr for the task of implies that crowdsourcing on the web is really beginning to become an accepted mainstream activity. Exciting stuff. I applaud the willingness of the LOC to experiment with social software.

More info is available at the Library of Congress website.