Sashiko is a traditional style of Japanese embroidery. First used as a form of repair, it evolved into a decorative style. The biggest idea in Sashiko stitching is a repetitive pattern, as seen in this adorable skirt above by Cherry and Cinnamon.
Craftsy.com has a great blog entry that includes more history on Sashiko as well as a tutorial for this cloud pattern.
I keep saying I am going to do this. Need to get cracking!