I had to take a calculus class to finally get my degree. This guy saved my ass, because I hadn't done calculus is like 15 years. I was soooo confused by his lectures, and I took the class in summer 6-week term. I was so scared I was going to fail and everyone in my class was complaining that he was a bad teacher. Well, I went to khan academy and I literally watched one of his 10 minute videos and understood. After spending hours listening to my professor, it was like the khan guy explained it in 10 minutes and I understood. I thought I got 100% on my first test, I understood it so well (I didn't, but it was from stupid mistakes).
DEFINITELY go to this guy's site. He is AMAZING. I got through calculus after not touching it for 15 years and scared shitless I would not pass.
I use free online maths lessons. http://www.youtube.com/user/GuruBix It is free. Step by step procedure to solve problem is given.Maths ticks also given to solve problems.
Great thread - most of these sites were already in my favourites
They're all good for different things, but imo the best overall is Khan Academy. Especially for maths/finance.
Slightly different, but another site I like to use is TED. It's less about learning facts and more about interesting/inspirational speeches. Even has one by Salman Khan from Khan Academy.