Not only does the library of congress have a blog they also started a flickr partnerships to share “more than 3,000 photos from two of our most popular collections [...] on our new Flickr page, to include only images for which no copyright restrictions are known to exist.”
If you want to read more about this you can read a blog post by David Weinberger or go directly to the original post.
another post on this at http://mashable.com/2008/01/16/flickr-library-of-congress/