I've used Paul's Online Notes for all my higher level math classes starting from Calculus 2. It has been more useful to me, even more than Khan's Academy. I like the little tricks and mnemonics that he teaches, especially in Linear Algebra. Example here: http://tutorial.math.lamar.edu/Classes/LinAlg/DeterminantRev.... Much easier way of calculating determinants.

Another resource I've used is Patrick JMT's excellent videos found at: http://patrickjmt.com. He really goes over problems slowly. Best math teacher I've ever had.