The American Orchid Society - OrchidWeb
The best orchid site on the web. culture info, bookstore and the best forum where I have to visit every day.

Internet Orchid Photo Encyclopedia 
Pictures and info of more than 2400 species!

NotSoGreenThumb
A great site with lots of high quality pictures, orchid culture and much more.

Linda's Orchid page
The first orchid site I found on the Internet. Should I blame or thank her? J

The Orchid Mall
Lots of links to good sites.

Orchid Forum
Another forum.