The Library of Congress has just announced a new collection calleed "Freedom’s Fortress: The Library of Congress, 1939-1953," available at http://memory.loc.gov/ammem/collections/freedoms_fortress/. The collection is comprised of 209 letters, memoranda, photographs, and Library of Congress publications (1,176 images total) and documents the history of LC during what is described as a period of great transition for the institution.
One cool aspect of this collection the timeline, which presents significant documents in a simple yet effective way (a feature that would be easy to mimic in other digital collections).