GPS receivers appear everywhere these days, integrated into smart phones, vehicle dashboards, cameras, and more. They're also shrinking—a variety of wrist-top models are available that track speed, distance, and location. There's a reason, however, why manufacturers dub these smallest GPS units "wrist-top computers" instead of "watches." They still require a linebacker-sized wrist to fit comfortably and are much chunkier than their timekeeping brethren. When will we see GPS watches small enough to fit us all?