The Drug Policy Alliance is a non-profit organization dedicated to ending the War on Some Drugs. It represents the amalgamation of the Lindesmith Center and the Drug Policy Foundation. Their main focus is in establishing harm reduction policies, such as syringe exchange programs.
Their website (www.drugpolicy.org) hosts a wealth of drug related information, including a description of the flaws in the War on Drugs, as well as a good overview of common drugs of abuse (if you're interested in more comprehensive info, as regards the chemical/experience aspect, erowid is a great site).
Of course, all of the relevant information here was gathered from the alliance's website.
www.drugpolicy.org