I didn't know about this - could be a great resource for images and classroom projects. Here's the link to the actual Library of Congress flickr page.
Read more - Flickr Works with the Library of Congress
The Library of Congress has launched its pilot project with Flickr. What began last year as a joint effort to bring the public library’s images to the web in a more organized and shareable fashion has finally become a reality. In conjunction with Flickr’s new program called The Commons, the Library of Congress has added about 3,000 of its millions of photos to Flickr albums so far.