When I read about the idea of a triadic color scheme within pages 38-66 I thought it was interesting to use such contrasting colors in art.  The idea of triadic color is to use hues from a triangular shape on the color wheel; three colors.  It is meant to create contrast and impact.  Here is a picture I found which represents this concept, and that I just plain like.  The artist used mostly red, greens, and purples which are equally spaced on the color wheel.  

It looks like the artist used the contrasting colors to make the light appear superbly-present.  It almost looks real even though you can tell it's a painting.