American Association on Mental
  Retardation [new name aaidd]

American Psychological Association

American Psychiatric Association

Association for Behavior Analysis

American Network of Community
  Options & Resources

Autism Research Institute

Autism Society of America  

Behavior Analysts Certification Board

Council for Exceptional Children

Developmental Disabilities Nurses Assn

National Resource Center of TBI
Travis Thompson's website
Professional Organizations & Service Agencies
Brian Iwata's website