http://www.brightstorm.com/
Brightstorm provides high-quality study resources for high school students. There are over 2500 free math and science videos of teachers teaching every topic in Algebra I, Algebra II, Geometry, Precalculus, Calculus, Trigonometry, Biology, Chemistry, and Physics. The paid parts of the Web site include additional study and homework help tools to help student prepare for the ACT, SAT, PSAT, and AP.