I don't use one. I have no fear of color! LOL I do change my mind sometimes as I go along though...sometimes something looks find in a pile, but not so much in the completed project.
One thing that some people don't realize is that you don't have to exactly match colors in quilts. You don't have to have the same colors in each fabric either. If you pick a focal fabric, then start working off of that adding colors that blend (not exactly match), and vary the scale of the prints, it's easier to come up with a combination.