Perfect Gaits
Rick Sermons is familiar with most of the popular horse trainers and their techniques from Parelli to Clinton Anderson and others. His advice on ground work and familiarity with gaited horses makes him a valuable resource. He’s not aligned with a breed and doesn’t train for show, but is more focused on helping people bring out the innate gaits in whatever breed they have and using ground work to assist problems. Humane methods only.
www.perfectgaits.com

Gaits Without Gimmicks
The late Lee Ziegler has published one of the best books on gaited horses entitled Easy-Gaited Horses.  This book answers many questions about gaits and how to ride and train gaited pleasure horses.  Last time I checked it was available at Amazon.com.
www.leeziegler.com

YAHOO!
Yahoo has several discussion groups about gaited horses and Fox Trotters. Do a search and see which are a good fit for you.
www.yahoo.com