You know those paths in a field or a park or a woodland trail, where enough people have walked and worn away the grass, leaving a line of exposed earth that is just one pair of footsteps wide? Those are called desire lines. I just thought that was a great name for them, and thought I'd share that with you. The lawn in Corbett Hall where I work is just littered with desire lines, and every time I see them I smile because of their excellent name. And now maybe you will have a lift in your day - or at least in your etymological knowledge - too.
(Above is the lawn of Corbett Hall as seen through the sattelites in Google Earth. The tuning-fork-shaped path is the actual paved path; all the other paths branching off from it are desire lines.)