The National Institute on Drug Abuse—the government's clearing house for information on drugs.
The Drug Policy Alliance—one of the leading groups advocating alternative approaches to the war on drugs.
Common Sense for Drug Policy—another anti-prohibition group. See especially their project "Drug War Facts."
Inter-American Drug Abuse Control Commission—coordinates policy for the Western Hemisphere.
The United Nations Office on Drugs and Crime. World Drug Report 2005 provides one of the most comprehensive overviews of illicit drug trends at the international level.