British Epilepsy Association (BEA) - provides a wide range of services and information to support anybody with an interest in epilepsy
Comprehensive Epilepsy Center of New York Hospital - Cornell Medical Center 
Comprehensive Epilepsy Program - Washington University
Cyberonics - they design, develop, manufacture, and market innovative and technologically advanced neuro-stimulation devices which provide efficacious and cost effective therapies for epilepsy and other neurological disorders
Epilepsy Canada - (English, French) is the only national non-profit organization whose mission is to promote and support research into all aspects of epilepsy, and to create awareness and understanding about epilepsy through educational programs
Epilepsy Circle of Support - site for parents of children who have epilepsy. There is a message board, chat room, and web site with essays, poems, photos, etc. There is also a child profile section for parent-to-parent contact.
Epilepsy Contact Database
Epilepsy Foundation of America
Epilepsy Foundation of New York City - their mission is to help individuals and families affected by epilepsy achieve their highest level of physical, social and emotional well-being 
Epilepsy: International.com (English and Spanish) - provides a large, comprehensive and well-designed educational and informational resource for those working with and/or dealing with epilepsy on a day-to-day basis
Epilepsy Ontario - provides client services, counseling, information and referral services, education and advocacy services for children and adults with epilepsy, and for their families
Epilepsy Circle of Support - here you will find information and support for parents of children who have epilepsy, youngsters living with epilepsy, and for everyone else living with or affected by epilepsy
EpiNet - Epilepsy Foundation of Victoria (Australia)
Infantile Spasms WebRing - includes personal stories of children with infantile spasms and other excellent resources
Ketogenic Diet - provides history of diet, links to sites, mailing lists, references, etc.
Ketogenic Resource - provides information on the ketogenic diet and related matters like epilepsy and cerebral palsy in young children. It is particularly intended for UK visitors, but most of the information is relevant to interested visitors, world-wide.
Parents Epilepsy Support Group - was founded as a means for parents and caretakers of children with epilepsy to share support, ideas, and express their concerns and hopes for our children
South African National Epilepsy League (SANEL)
Surgery for Epilepsy
University of Washington Regional Epilepsy Center