The Color Game by Ted Naos includes a series of colored cards with different cut-outs and instruction cards. They measure roughly 3.5 x 3.5 inches square.
The instructions include basics about color theory, including a list of color harmonies from Chevreul and a mini-color wheel.
You can use the color wheel and information included with the game to play with different color combinations. And hey - the square shapes start to look like quilt blocks, am I right?
Here's an analogous combination, colors next to each other on the wheel. Once you find a combination, you can play further by switching up the cards to get different effects with the colors.
Here's an example of a complementary pair below with greens and red.
And there's a few white and black color screens, which can also give different effects with the same sets of colors. Check out the red/blue combo with white and black below. Even the settings on my digital camera reacted differently between the white with the red/blue and the black with the red/blue, you can see it in the way the camera read the table differently in each photo.
I played with this for about an hour when I brought it home, and I really like it! Especially the way you can easily switch around the colors to see immediate results with the interactions between different colors. And as a bonus, the little jewel case for the game can be used as a little stand if you find a combination you really like!
You can click through to the Ted Naos website at the link above to see the many sets offered - this is the basic set. There's a pretty awesome looking Street Architecture set where these cutout cards are shaped like different buildings, and some other neat-o shaped sets, too.