The best class I ever took was chemistry. It was taught by a clinical psychologist and a former maximum security inmate (15 years). Throughout the term we had former inmates in to discuss things with us. The subject matter was profoundly interesting and the instructors worked amazingly well together.
The second best course I have attended was probably my Medical Ethics and Professionalism. The course was held in the afternoon one day each week. One week the topic was the role of the Third Reich physicians in the events leading up to and surrounding the holocaust. We had a panel of speakers that consisted of the son of a German physician who fled Germany and 6 WWII veterans. Each of these veterans had something in common: They were members of units that discovered concentration camps or POW camps. They spent 3 hours telling us their stories. It was both chilling and inspiring. The instructor for the course was a young pediatrician and ethicist, and is also one of the greatest people I've met in my life.