Paph and Phrag Links An AWESOME, increasingly large site that is packed with information, including species specific culture sheets, photos, taxonomy and blooming seasons, among other things. I'm amazed with the info available at this site each time I visit! Awesome work, Stephen! This site has pictures and basic cultural info about most paph species
Antec Reading Room Bob and Lynn Wellenstein's info archive. Great in-depth information in here! Nice plants, too!
AOS Paph Culture Sheet Simple information for beginners. A good place to start! Great species-specific information about Phragmipediums, and some nice pictures.
Paph. Culture Guide This site offers a well referenced bit of information about most of the known paph species. Not a beautiful site (probably due to lack of space) but plenty of information.
Slippertalk Forum A wonderful online community of Slipper Orchid lovers! Tons of great info, lots of nice people, including vendors and novices. You'll see me post as Gore42.
The Orchid House OK, this isnt really just for Paphs and Phrags, but it has such a wealth of useful information that I thought I'd put it at the top here. They have lots of information about growing under lights (and understanding lighting), among other things.
Dr. Tanaka's Paph World, also full of information about Phrags. Ok, so the English is sometimes questionable, but the website has an enormous amount of useful information. One of the best Paph sites in the world! Can't summarize, you'll have to take a look.
DENVER ORCHID SOCIETY forum! So it's not slipper specific. But it promises to be a great forum for those in the Rocky Mountain States! Join up now and be a founding member! Rumor has it that the forum Administrator is pretty cool :)
Disa culture and species information
Diablo Disas Culture Page Diablo Disas is now defunct, but their wealth of info is still published online.
The Disa Philes An archive of Disa related information newsletters.
Merkles Disa Page Interesting stuff here. Info on how to make a flood tray from Disa culture.
Zephyrus Orchids Disa Page Just to show that other people think Disas are easy. Some good growing info, too.

Still, one of the few places that sells Disas. Especially useful if you're Canadian.

Orchid Conservation Links
The Ceiba Foundation for Tropical Conservation This is a great conservation group! They offer volunteer opportunities and courses of study in Ecuador and other tropical regions, as well as information about their native orchids and orchid propogation in general. A great idea for those of you who want to offer "hands-on" help!
The US Botanic Gardens Conservation Pages There is some information here about orchid conservation, and more generally, plant conservation.
The AOS Conservation Pages The AOS has various programs to help endangered orchids, locally, and around the world.
Orchid Conservation International An orgainization dedicated to saving endangered orchids, with an all-star staff of trustees, including Dr. Phillip Cribb.
The Dokmai Garden Orchid Ark A truly great conservation organization, the Orchid Ark protects orchids in their natural habitat and in gardens, propagates endangered species, and raises awareness of damage to habitats.
Other Orchid Genera culture information
The Internet Orchid Encyclopedia This is an amazing database, with photos and habitat information about nearly 6000 orchid species. Very useful!
Orchid Species Culture Sheets (Pay Service) This page has quite a few free samples, but the bulk of the information is on a "pay-per-sheet" basis.