MIT OpenCourseWare
I’ve just discovered the power of MIT OpenCourseWare. The notes there are comprehensive enough to study for my YDSP attachment. There are more details given there than on Wikipedia. I’d be severely remiss if I did not recommend this excellent source of materials for self-study. They have a wide range of topics covered, though you should keep in mind that it’s very subjective towards the courses that MIT has.
URL: http://ocw.mit.edu
Bookmark it, people. 
