Quite a few maps have used Red and Blue to represent Democratic and Republican states. The problem with this is that Red and Blue are not opposites. Red and blue will naturally produce purple when put in close proximity to each other. Therefore many maps that use Red and Blue produce a purple America.
Instead, I have used Red and Green to produce my map. I have chosen values so that when 50% of the red is mixed with 50% of the green, the result is a neutral color. I have also scored the results on a bell curve style distribution. Utah is pure Red, because it was the strongest Bush state, while Massachussetts is pure Green.
The result is, I think a map that accurately shows where each canidate has strong support, while at the same time showing the areas that are much more evenly mixed. Indiana is a much stronger Bush state than Ohio was, for example, and I think this map shows that off well.