Library of Congress Prints & Photographs Online Catalog (PPOC).
“The Prints & Photographs Online Catalog (PPOC) provides access through group or item records to about 75% of the Division’s holdings, as well as to some images found in other units of the Library of Congress. Many of the catalog records are accompanied by digital images–about 1.2 million digital images in all.”
Update: On April 7, 2010, Library of Congress announced in a blog post the release of a new version of this database , which provides new features such as “sharing tool” and new ways of browsing. It also has a new and easier to remember web address: http://www.loc.gov/pictures/.
What do you think of this resource?