Prismacolor Color Wheel
How To Choose Colours That Work Well Together – Infographic | Cool Daily Infographics
Easy ArtSpace - Colours
A better explanation than I've ever gotten from a teacher or book. This could be the wiki for color theory: Why do some color schemes work, and others don’t?
Vintage Colour Wheel featured on Bambino Goodies
And a little extra: If you add primary colors perfectly they create grey Complimentary colors create brown It is possible to make black by adding a bit of the colors until you are at the correct color
Jane Blundell: Colour exploration - a single pigment colour wheel
Setting for Four: Tried and True Color Trios - This blog post changed the way I think about design.