Khan Academy

With a library of over 3,000 videos covering everything from arithmetic to physics, finance, and history and hundreds of skills to practice, we're on a mission to help you learn what you want, when you want, at your own pace.

https://www.khanacademy.org/

Adobe Kuler

Create color schemes with the color wheel or browse thousands of color combinations from the Kuler community.

https://kuler.adobe.com/

Color Scheme Designer 3

A designer tool for creating color combinations that work together well. Choose your color range and arrange it easily.

http://colorschemedesigner.com/