"William P. Gottlieb: Photographs from the Golden Age of Jazz" is a digital exhibition put together by the Library of Congress for it's American Memory project. It consists of over 1,600 photographs taken by Gottlieb from 1938 to 1948 while he was writing for Down Beat magazine and the Washington Post. The site states that the reasons for digitizing this particular collection involve it's unique portrayel of an important era of American music. The collection can be browsed by artist, subject (essentially genre), and the individual venues where the photographs were taken. Visitors can also search the collection using keywords.
Extensive metadata is provided for each item in the collection, including size and format of the original image, when and where it was taken, the publication it appeared in (if applicable), and the artists who appear in it. Library of congress call numbers are also provided. Additionally, each image is tagged with multiple subject descriptions, though the method through which they were applied isn't mentioned on the site. A link at the top of each photographs page links visitors to rights and reproduction information.
The digital objects themselves are jpeg files, and clicking on a thumbnail brings the user to a larger version of the image (often with selections for multiple higher resolutions). The images themselves are of good quality, though lossless formats aren't available. Each image is given it's own digital ID, which consists of 'gottlieb' and a five digit number. Specifications were created for the different versions of the image (thumbnail, compressed, large compressed, archival) and these specifications are made available on the site.
All in all, this is a well organized collection that would be of use to jazz/music historians, or even people with a pazzing interest in the music and artists involved. The purpose of the "American Memory" LoC sites seems to be just that: making history and culture available to anyone who might look for it.