A wealth of Orchid facts and helpful hints:

Ionopsis
On this website you will find anything about orchids: how to grow them, history, interesting stories and lots of pictures.
http://www.ionopsis.com/old_orchidgrowing_index.html

Orchid Board - Most Complete Orchid Forum on the web!
http://www.orchidboard.com/

The American Orchid Society
The American Orchid Society is more than just a flower club. Throughout its 85-year history the AOS, in keeping with its vision and mission, has strived to bring our members timely and state-of-the-art orchid information, support basic and applied research in orchids, and monitor and support conservation effort both here in North America as well as throughout the World.
http://www.aos.org//AM/Template.cfm?Section=Home

Orchids of the World
http://www.orchids.mu/index.html