National Resource Center on AD/HD
Clearinghouse of information and resources about ADHD

Attention Deficit Disorder Association (ADDA)
Resources for adults with ADHD

Children and Adults With Attention-Deficit/Hyperactivity Disorder (CHADD)
Resources for children, adolescents, and adults with ADHD

ADDitude Magazine
The nation's leading ADD magazine

ADDvance
Resources for girls and women with ADD

ADD Consults
All kinds of neat stuff for sale 

A.D.D. WareHouse
Books, videos, games, many other products for sale

National Institute of Health (NIH)
Information on biomedical research, diagnosis, & treatment

Centers for Disease Control and Prevention (CDC)
A wide variety of ADHD topics

The Hallowell Center
Dr. Edward Hallowell's website

Sari Solden.com
Women with ADHD

Dr.Thomas Brown.com
One of the world's leading scientific experts