I think I've posted before about MIT OCW for uni level maths. Apparently they have now got a website for high school students.
You might find some of the stuff about AP calculus helpful.
http://ocw.mit.edu/OcwWeb/hs/calculus/calculus/index.htm
You might find some of the stuff about AP calculus helpful.
http://ocw.mit.edu/OcwWeb/hs/calculus/calculus/index.htm