Take University Courses for free over the Web. Type in your subject. Check out the courses available. Now you to can study cognitive robotics at MIT, pathophysicology of infectious diseases at Tufts, or causal and statistical reasonaing at Carnegie-Mellon. Or how about some artsier stuff?
The MIT site also includes the Sloan School of Management and they have a whole slew of free courses devoted to turning you into a corporate uber-meister. Make money fast! Yay!