FRANK could be a tremendous resource for parents trying to figure out what is going on.
I think FRANK is located in the United kingdom. I immediately thought this would be a great starting place for parents who have a kid with a drug problem. Alcohol is certainly not the only drug kids experiment and get into trouble with.
This site has a huge list of street names for drugs. Concerned parents and friends might look here to find out what names mean and if their kid is talking about them, what effects the drugs have.
There is live chat and email resources. If you live in England you can type in a postal code and locate treatment services in you neighborhood.
Anyway, you want to have as many resources as you can. You never know which resource will answer your specific question.
Here is another resource that is less technical. Simple English Wikipedia
Depending on what you are trying to find out about this can be a good source. They have some decent definitions and explanations.
Here is a sample page on Heroin.