Khan Academy: With a library of over 3,000+ videos covering everything from arithmetic to physics, this is a fantastic resource for kids to learn at their own pace.
Code.org - This nonprofit is dedicated to growing computer programming education. Check out the site for a collection of coding resources.
Scratch - Created by MIT Media Labs, this amazing free resource helps young people learn to think creatively, reason systematically, and work collaboratively all the while creating some really cool interactive stories and games
Stencyl - Stencyl uses a highly intuitive block-snapping interface inspired by the popular MIT Scratch project to teach kids as young as 6 how to code by building their own games