The New York Public Library's digital collection is vast... and just got better. On January 5, NYPL announced the conversion of more than 180,000 high res images from copyrighted to the public domain (see Free for All: NYPL Enhances Public Domain Collections For Sharing and Reuse).
Wrote library staff,
Today we are proud to announce that out-of-copyright materials in NYPL Digital Collections are now available as high-resolution downloads. No permission required, no hoops to jump through: just go forth and reuse!
But the news is more than just the release of documents, old photographs, and illustrations. The library has launched a visual browsing tool "to help patrons understand and explore what was contained in that release." The tool is wicked cool and makes exploring fun. Fair warning, though, it's easy to get lost in time and resurface hours later.