If you feel like you might be a bit behind on your education or you need a refresh of some subjects, you might be interested in the Khan Academy.
You can learn about maths, art, computer programming, biology, finance, medicine, history and more.
They say:
Khan Academy is an organization on a mission. We’re a not-for-profit with the goal of changing education for the better by providing a free world-class education for anyone anywhere.
All of the site’s resources are available to anyone. It doesn’t matter if you are a student, teacher, home-schooler, principal, adult returning to the classroom after 20 years, or a friendly alien just trying to get a leg up in earthly biology. Khan Academy’s materials and resources are available to you completely free of charge.
I haven’t actually had a chance to do any of the courses yet, but they looks really good and the reviews of the site are extremely positive.