Easy Rider is a truly landmark film in the true sense of the meaning of the term.  Produced on a very low budget and set in the late 60's it was, in my opinion, the first movie to really capture a particularly interesting moment in time.  While many films sort of used the notion of the late 60's, drugs, sex, rebellion, idealism, as a means to make money, this seemed really the first film to accurately reflect a realistic image of the time period with an unflinching eye.