Alexandra, my 13-year-old daughter, taught me this nifty trick...Using Google's "Picasa," I was able to place spot color on a black and white picture in seconds. Most people use something like Adobe Photoshop to select an area with a "lasso" tool, then invert the rest of the picture into b&w.
With Picasa, you just move an adjustable "wand" tool over the area you wish to leave "in color." Viola, instant color highlight. Now, I could send this image to Walmart's Online Photo Center and have wallet-sized pictures ready for pick-up in an hour. Very cool!