Khan Academy is a non-profit with a goal of offering a free, world-class education to anyone, anywhere. I noticed that Khan Academy was the iTunes App of the Day yesterday (Android link), and I found that they have definitely made a lot of improvements since the last time I used it. There seem to be more interactive questions and the app interface is much cleaner. I remember when it was just a bunch of videos. The iPad app now includes handwriting recognition.
I would say the content focus is still on the K-12 level and college prep. Khan Academy covers everything from counting to alegbra to computer science to world history. In fact, they are now the official practice partner for Advanced Placement (AP) tests. They also offer free SAT test prep (MCAT, GMAT too + LSAT coming soon) along with college admissions assistance. Yes, they even have a section on personal finance! All free with no ads. Check it out if you haven’t recently.
Great opportunity to obtain valuable knowledge and skills!