Not specifically for higher level math, but I found this concept driven approach to the times tables pretty cool:
http://www.visual-learners.com/support-files/nbf-6-9-10.pdf

Definitely like Khan Academy, if for no other reason than how cool their Math Map is:
http://www.khanacademy.org/exercisedashboard

And not sure how the MIT stuff is presented, but likely worth a link:
http://ocw.mit.edu/courses/#mathematics

And what could be more fun than exploring old math competition stuff; the AMC site has some cross-links to various competitions as well as problems from some of their annuals.
http://amc.maa.org/a-activities/a7-problems/problemdir.shtml