The Ghost of Hamlet's Father:
If we read Hamlet as a psycho-drama, we might view the ghost simply as Hamlet's inability to accept his father's death. While this could conceivably lead to insights about some aspects of the play, it is difficult to relate this model to the significance of the play as a whole. A more useful, and certainly more exciting way of explaining the symbolic significance of the ghost is to use a Freudian Psychoanalytic model. Could Hamlet be suffering from an Oedipus complex?
(hey, if you're wanna talk psycho-drama, you might as well go all the way...)