The Khan Academy is a not-for-profit organization with the mission of providing a high quality education to anyone, anywhere.
We have 1400+ videos on YouTube covering everything from basic arithmetic and algebra to differential equations, physics, chemistry, biology and finance which have been recorded by Salman Khan.
With a broad range of science topics, this site ist totally worth looking at.
Need to update your knowledge on algebra, calculus or physics?
Its not shiny due to the low production buget, but the information is available free under a CC3 license.