http://burnsarchive.com/index.html
vernacular photo archive:
including medical, historical, crime, death, war

http://www.gaylord.com
archival supplies, info about storing photos

http://www.kaufmanelson.com/index.html
vintage photo experts – sales and services

http://iphotocentral.com/index.php
sales site for professional photography, with section on collecting issues and resources