Here is an interesting documentary brought to us by the history channel. I think this is one episode of a series they did but its the only one I have. The documentary focuses on opium, and how its evolved through time into heroin.

http://rapidshare.com/files/163597537/History_Channel_Illegal_Drugs__opium_.part1.rar
http://rapidshare.com/files/163601754/History_Channel_Illegal_Drugs__opium_.part2.rar
http://rapidshare.com/files/163606011/History_Channel_Illegal_Drugs__opium_.part3.rar
http://rapidshare.com/files/163586688/History_Channel_Illegal_Drugs__opium_.part4.rar
http://rapidshare.com/files/163590526/History_Channel_Illegal_Drugs__opium_.part5.rar
http://rapidshare.com/files/163593687/History_Channel_Illegal_Drugs__opium_.part6.rar