Khan Academy

Whether you are in kindergarten or getting ready for college, this site is a great resource for any math problem or science concept you may be struggling with. What's even more amazing is the entire collection of over 1,600 videos is compiled by the founder, Salman Khan, whose only mission in life is to make you smart! So be sure to add it to your favorite bookmarks and refer to it whenever a problem stumps you or just watch it for the fun of learning - That's what Bill Gates and his son do!