I haven't done it in a while, but you can do cubes (and more) too. Cubes would be the L3 norm, something about the distance between circles (spheres?) in 3d space? I need to read about norms again to tell you why or when to choose that, but I know the Googlable term is "vector norms"

I remember one is Manhattan distance, next is as-the-crow-flies straight line distance, next is if you were a crow on the earth that can also swim in a straight line underwater, and so on