Google Maps on the Down Slope

The Hill Mapper San Francisco makes great use of the Google Maps API Elevation Service to show the direction of the slopes on San Francisco's streets.

The uphill streets are colored red and the blue streets go downhill. The darker the color of the street, the steeper the hill. If you move your location on the map the colors of the streets dynamically update to reflect the new directions of the slopes, relevant to your new position.

I'd love to see cycling directions added to this map, with a route dragging option, so that you could plan a cycle route that avoided steep uphill climbs.