I've always liked the Tortoise Reserve - they have common sense conservation efforts (for both chelonian and crocodilian species), and a few small captive breeding efforts. http://www.tortoisereserve.org/

There's also the MARS Preservation Fund, Inc. - all funds donated to MARS goes to purchase rainforest in Costa Rica. They also donate money to resarch IBD or "star gazers" disease in snakes - one of the few organizations to do so. If a donation were made to MARS, I'm sure you could have it ear-marked for the IBD research (done by Dr. Elliot Jackabson at University of Florida www.vetmed.ufl.edu/sacs). See http://reptileinfo.com/donor.html for more information.

Katrina