For those interested in the early history of photography -daguerreotypes, ambrotypes, calotypes etc., I can recommend the following sites :
[B]The Daguerreian Society
http://www.daguerre.org/home.html
[B]The Library of Congress - Daguerreotype Portraits and Views
http://lcweb2.loc.gov/ammem/daghtml/daghome.html
[B] Lost and Found - Rediscovering early photographic processes
http://imsc.usc.edu/haptics/LostandFound/t...uerreotype.html
http://imsc.usc.edu/haptics/LostandFound/t..._ambrotype.html
[B] University of Glasgow - The Calotype Process
http://special.lib.gla.ac.uk/hillandadamson/calo.html