To see a video on how to pick up only a certain color in Adobe Photoshop and leave the rest black and white click here. I also recommend checking out this one. It's not the one I used, but the guy has a ton of awesome Photoshop tutorials and his way of bringing up one color is also pretty easy.
After printing my pictures, I put them into a photo book (I found it at the store for about two dollars), and added some scrapbook letters to title the colors.
Black and gray were difficult colors to point out in a black and white photo so I edited them in the free downloadable program Picasa. If you don't have it--I highly recommend it. I chose the effect "focal b&w" on the black or gray parts from the picture so a little bit of color is around the black or gray item emphasizing the color.
I added the special wording at the beginning and end to add sentimental value. This would make a great gift for kids and now you can just grab photos from someone's Facebook so you don't even have to ask for pictures!! It would be cute to do as a combo color and favorites book too (a boy's favorite red car, his special blue blanket, his special brown bear...).