On Google maps you can edit the live maps that are seen by everyone throughout the world and it lets you add info about if its a bike path, ped path, no sidewalk, dirt road, locked gate, etc. So maybe an app like this would get runners to slowly start inputting data about the areas around them, improving the maps accuracy for everyone.
It does sound like a great idea.
You can almost come close by doing the get directions, and put in your house address and the house address of your neighbor. Then click on the path and drag the pin to anywhere that you want to walk past. It will you give a route to your neighbors house via wherever you put the pin. And it tells you how far it was. And if you click on the "walking" tab it will even include walking paths if your town has any (we have a very large network of walking/biking paths here in Davis) and Maps did a pretty good job using them.
