Here is a link to some public domain pictures:
http://www.publicdomainpictures.net/

Primary Source Documents: http://lib.washington.edu /SUBJECT/HISTORY/rusa/

This link is to the Smithsonian's National Portrait Gallery: http://www.npg.si.edu/.

Here is a good blog link to find multimedia tht is copyright free for use on the web: http://mashable.com/2009/08/04/free-blog-media/.

Royalty Free Sounds: http://www.soungle.com/