Have you seen this? It's Adobe's color wheel. You can manipulate the rays in the circle to change the colors in the bars beneath. On the left you can choose between Analogous - Monochromatic - Triad - Complementary - Compound - Shades - or a Custom view. It is very addictive to just play with color.
Find it here and try for yourself.
Imagine how you can use this in art for choosing colors. Here is one of my favs from this mornings go at it.
There is also an App you can download for your I-phone. It has a really cool feature in that it uses the phone camera and adjusts the colors in the bars based on what it seen through the lens. Oh technology...I gotta love you.