Apart from being a great film, Hitchcock's Psycho has the darkest opening title sequence ever, and the first time I saw this film, the following short looped excerpt had a stronger effect on me than even the infamous Shower Scene.
It wasn't until much later that I found out that the creator of these titles, Saul Bass, was a total genius, responsible for many great film titles.
The Psycho effect, with the lettering becoming sharply disjointed, reflects the schizophrenia of the main character, Norman Bates.
For me, however, it also looks like a computer going wrong, displaying a fragment of corrupted memory. Obviously, back in the 1960s, Saul Bass couldn't have forseen this sort of interpretation!
This is a very comprehensive site: SAUL BASS ON THE WEB
Also, Click here for an excellent in-depth article about these titles and Saul's methodology. Also includes a full Real Player file of the opening titles and music.