USA Judo - National Governing Body for Judo in the USA

United State Judo Federation - Group A member of USA Judo

United States Judo Association  - Group A member of USA Judo  - The best overall Judo resource on the Internet.

World of Judo and Ju Jitsu  - Good source for information on history of Judo           

The Kodokan - Home school of Judo           

International Judo Federation - World Governing Body for Judo