The press recently covered these free online tutorials at http://www.youtube.com/user/khanacademy?ob4
Offered by Khan Academy, who write "It is our mission to accelerate learning for students of all ages. With this in mind, we want to share our content with whoever may find it useful. The videos have been categorized within the playlists."
Subjects include: Arithmetic, Pre-Algebra, Algebra, Trig, Pre-Calculus and Calculus.