I received an email asking about a good online resource on substance abuse and related topics. There are quite a few out there that are sponsored by different health organizations and other groups. The one link I generally use is the one connected to the Office of Drug Policy in Washington DC.
This link can direct you to a variety of different topics and information on specific substance abuse issues and or drugs.
It is by no means the only one out there but is generally consistent and accurate in the information provided.