a gray-scale really comes in handy when working on water-color quilts, helps you really see the light/medium/darks without the colors getting in the way. i have found i can easily set up 2 piles of squares--lights and darks---but when you start putting mediums in to the mix .... a grayscale ! you can also clip little (swatches) of your fabric glue them in order to a piece of paper, scan then print in grayscale. again, this will help you see the values of the fabrics