Groovy-ghan free pattern (I made this afghan with my grandmother's scrap yarn, when I was 15 years old. she taught me two stitches, and I was "hooked". That was 34 years ago, I still have that blanket, and it's as groovy as ever.
The author of 50 Ripple Stitches, Darla Sims, has provided a must-have reference book of fabulous ripple stitches. As you can assume, there are 50 great patterns to choose from that use the ripple stitch.