In Boulder, Colorado, Pedal to Properties is a full service real estate company that keeps a fleet of bicycles for clients to use on showings. They go out every Wednesday night with their clients on bikes.
There is a Coldwell Banker-Gundaker in the Benton Park Neighborhood of St. Louis, that has what they call the "CBG Bike Garage." They provide bike showings for perspective buyers. Its probably the best way to tour that neighborhood.