Sigmund Freud really contributed alot to the field of Psychology. Before him people didn't really have anywhere to go if they had a psychological problem that they needed to deal with. Many of his theories have managed to trickle into everyday speak. Whether it's people talking about slips of the tongue or speaking about analyzing their behavior.
Since the time of Freud the field of personal development has made tremendous progress. Though I personally don't subscribed to practically any of his theories that I know of I still appreciate his boldness and his influence on the field of psychology.