MIT OpenCourseWare etc.

There are some useful instructive Internet sites that you can gain a lot.
You can watch (,listen to, or read) some lectures of unis for free.
(Please note that none of them I found by myself: there were some people who recommended them on the web.)

Free Online Course Materials | MIT OpenCourseWare
Academic Earth | Online Courses | Academic Video Lectures
YouTube - ‪Education - YouTube EDU‬‏

You should also make the most of iTunes U.
All you have to do is to get iTunes for free, connect to iTunes store, and hit iTunes U on the top of the screen.
You will find numerous lectures there. I almost fainted with joy. haha