Alternative Photography.com
The best source for all things alternative photography. The site includes technical information on all major alternative photographic processes, how-to articles, a gallery of members' work, books and magazines, and links to suppliers.

Bostick And Sullivan
A wonderful resource for all kinds of supplies used in alternative photography processes.

Any Colour You Like
This is a very informative article about the history and process of hand colored photography. This link leads to part I of a four part article, be sure to check out the other sections, which can be accessed from the part I page.