RHS.org.uk
The Royal Horticultural Society
Sally Robertson
Sally Robertson is a well-known water color painter and has a beautiful site of orchid, rose, and other flower watercolors. Originals and well as prints are for sale on the site.
"Google" the name of any orchid and you will find out more than you ever wanted to know. Same for "YouTube" orchid repotting demonstrations. Watching someone repot can be very helpful.
My current favorite books (Don't forget Books!)
A Compendium of Miniature Orchid Species, volumes 1 & 2
Tremendous effort by the Ron Parsons and Mary Gerritsen, gorgeous photos and lots of information.
Wild Orchids of Thailand
Nantiya Vaddhanaphuti
Growing Hardy Orchids
John Tullock
An Enthusiasm for Orchids
John Alcock
Orchid Growing Illustrated
by Brian and Wilma Ritterhausen
Most anything by the Ritterhausens is good, clearly written, with helpful pictures and lots of practical information.
Home Orchid Growing
by Rebecca Northern
A more advanced book on orchid culture, no one should be without this classic. Getting harder to find, but worth the work.
The Wild Orchids of California
by Ronald Coleman
Very informative if you want to look for the Orchids in California
Cattleyas and Their Relatives (in 5 volumes)
by Carl Withner
A really impressive work on the Cattleya alliance species. Lots of good information, beautifully organized.
Orchids Species Culture
by Margaret and Charles Baker
A series of books packed with very specific information as to climate and habitat of different species. See their web page too for great information.
Dendrobium and Its Relatives
Lavarack, Harris, Stocker
A great resource for Dendrobium lovers. Cultural information and photos
Flora's Orchids
Isobyl La Croix
Timber Press
Solid general information and photos of all the major orchid types
Orchid Fever
Eric Hansen
A great read. Eric has traveled and talked with orchid people all over the world.
Orchids of Mexico
Hagsater, Soto, Salazar, Jimenez, Lopez, Dressler
A truely great resource.