Carol Highsmith is a photographer who, inspired by Dorothea Lange, documented each of the 50 United States. Since 1988 she has dedicated her photos to the public domain, and has even fought stock photo companies in court 
(unsuccessfully) to ensure the photos are not inappropriately claimed under their copyright.
This makes for an excellent collection of photographs for experimenting, without needing to worry too much about copyright, in an environment like Federated Wiki.
(Same URL imported, fed wiki style, is below)
Highsmith, a distinguished and richly-published American photographer, has donated her work to the Library of Congress since 1992. Starting in 2002, Highsmith provided scans or photographs she shot digitally with new donations to allow rapid online access throughout the world. Her generosity in dedicating the rights to the American people for copyright free access also makes this Archive a very special visual resource. site
Below is a page which I believe David Bovill used his Activity transporter to import from Wikipedia.
__Carol McKinney Highsmith__ (born __Carol Louise McKinney__ on May 18, 1946) is an American photographer, author, and publisher who has photographed in all the states of the United States, as well as the Washington, D.C., and Puerto Rico. She photographs the entire American vista (including landscapes, architecture, urban and rural life, and people in their work environments) in all fifty U.S. states as a record of the early 21st century - wikipedia