Nice concept. I'd still like to see someone tackle an editor that made model/map entity based construction as simple as Dan's Arch-E. It works for it, but the grid is too small to really go to town on it. I envision something using splines and then when you click create/generate, it uses the splines to construct the road. A sidewalk feature would be nice, too. I guess it'd be like Maple3D's MAX MAP utility.