I have always (for about 25 years actually) saved my scraps of yarn after a project - I just can't throw them away. After collecting a few, I like to roll them into a ball (this scrap ball weighs 15 ounces) and crochet them into an afghan. It's almost like getting a "free" afghan.
Sometimes I like to separate the dark colors from the light colors and sometimes I don't. This time I didn't, but the last time I made a scrap afghan, I only used the light colors. It came out real pretty. You may remember the round ripple I crocheted the last time I went to the campground - if not, here it is: