I found a different kind of color wheel in a little quilting supply booth in a craft mall yesterday. It's called the Rainbow Color Selector from EKSuccess. It has windows that you place over the color you are trying to match, you pick the closest color match on the wheel, then it points to the coordinating colors depending on what color scheme you are looking for. It's a little hard to describe--you can see it here:
http://www.scrapbook-creations.com/pocsizrainco.html
The color guide that comes with it discusses the different possible color schemes (monochromatic, triad, etc.) and is very useful.
I got it for under $4. but it seems to be running a bit more ($5.50-6.00) online. Do a google search for Rainbow Color Selector and you'll find a lot of sources.
Cyndie