Jane LaFazio featured this on the Sketchbook Challenge blog and I just LoVe it! It's slightly annoying in that it doesn't seem to be able to see yellows but I think it really has potential re looking at the colours you use in your work, and I also think that the swatches would make a great starting point for a second piece of work.
I did the circle painting first and was a bit disappointed by the results. As you see, no yellow! But my other image choices gave better results.
The program is called 'Colour Generator'. You just upload a photo and it creates a number of swatches featuring the colours you've used. Cool isn't it?!!