As a student who wishes to pursue pharmacology with a focus in controlled substances, this website is almost like an entire college degree. I can study molecular structure, contraindications, psychoactive effects, combinative effects, history of use, dosage, and read first-and-third-hand experiences with nearly any psychoactive imaginable. Without Erowid, this information would be difficult to collate, even on one substance alone, not to mention the hundreds covered in Erowid's extensive Vaults. Perhaps the most useful site I've ever visited.