NANPA is focused on nature and environmental photography, to promote nature photography as an art form and a medium of communication for the sciences, nature appreciation, and environmental protection.
This site details the beginnings of photography from 1825 to 1920, including significant people in the early history of photography, and significant processes, styles and movements.
By Philip Greenspun, this is an impressive compilation of photographic resources. There are many original technical articles, as opposed to just lists of things. Good photo essays too.