After I went to Bonnaroo and saw people doing every drug imaginable, I read "Buzzed" [0], which is written by several Duke professors and covers just about every drug out there. It was really fascinating, and I was surprised to find that many drugs are not that harmful, or at the least not nearly as harmful as I assumed them to be.

[0] http://www.amazon.com/Buzzed-Straight-Abused-Alcohol-Ecstasy... (not an affiliate link)