Psychology certificate through self-study?

I've found a wealth of really interesting psychology courses OCW (see MIT and Berkley, among others). I believe by watching all of the courses, completing the assignments, and reading all of the books in the reading lists, I could build a fairly valuable set of knowledge on the subject. I'd just lack the interaction with a professor. Is there some way I can translate self-study into a valuable certification of some sort, say, through testing or a portfolio? My career area is education, and knowledge of psychology seems relevant to that.