Some links that may be useful:

American Society of Icthyologists and Herpetologists (ASIH)

http://www.asih.org

AmphibiaWeb

http://www.amphibiaweb.org

The Center for North American Herpetology

http://www.naherpetology.org/

The Reptile Database

http://www.reptile-database.org/

IUCN RedList (formerly Global Amphibian Assessment)

http://www.iucnredlist.org/

The Herpetologists' League (HL)

http://www.herpetologistsleague.org/en/index.php

Society for the Study of Amphibians and Reptiles (SSAR)

http://www.ssarherps.org