Erowid.org is prob the very best drug information database on the internet. Any questions you might have about drugs, the effects, history, laws, and so on is all here on this website.
Another good site for drug information is Trip Project. They take part in the Rave/Counterculture community in Toronto and the rest of Canada, giving free cut-up straws for snorting, condoms, and drug info pamphlets all free of charge.