Well, I'm sure you've all heard of Sigmund Freud. He's probably more famous than anyone else in the field.
Then there's Carl Jung, who I mentioned in another thread. Much of his work deals with an idea called the "collective unconscious" which refers to traits in the subconscious that are common in all humans. He also talks about the Self, the Shadow, the Anima and the Animus, which are quite interesting.
Another interesting guy is Friedrich Wilhelm Nietzsche. He dealt more with philosophy in general than the subconscious, but some of the things he worked on were a big influence on Freud.
Finally, if you want something that's pretty far "out there", look up Drunvalo Melchizedek. Some of the more interesting (and more difficult to swallow) ideas of his deal with the evolution of species through the completion of "grids" which connect the consciousness of entire species. He says that humans will eventually evolve and pick up an extra pair of chromosomes. Most interesting is his theory that the consciousness of all humans are connected together and will some day be able to work as one entity.
The sacred geometry stuff he talks about is really cool though. And even though his ideas seem far-fetched, he at least has a good message about peace and unity.