Stat Trek: Teach yourself statistics, learn things from another perspective or review basic statistics on this site. It's a great reference for studying or getting self help with homework.
Purple Math: Review basic algebra concepts. They have great tutorials, and a great place to brush up on your algebra skills.
Visual Calculus: A great set of Pre-Calculus and Calculus I notes.
Wolfram Alpha: An unbelievable online computational engine.
MIT OCW: A collection of free online lecture video, notes, homeworks, and tests from MIT. Similar libraries are available from Yale, Havard, etc.
OYC Yale: A collection of free online lecture video, notes, homeworks, and tests from Yale.
edX Harvard: A collection of free online lecture video, notes, homeworks, and tests from Havard.";