Tackling high school math? Math TV is a great source for help. It has videos of teachers explaining all kinds of math problems, step by step. So if you need some more worked examples and more explanation on any topic from fractions to derivatives, this is a good place to look. It would be a great backup for Khan Academy for when you just need to see more problems worked through. They also offer online textbooks for a reasonable price. If you use their textbooks, the videos are all sorted and displayed for each chapter. The videos themselves are free to watch, can be sorted by category and most are available in Spanish as well.