I have built this mashup to show home value estimates, mortgage rates and comparable sales data for a given residential property. Zillow provides APIs for these and much more as shown at my web site www.elixiraddons.com. The details are presented using Google maps API.
Recently, I have enhanced this using Urban Mapping API to overlay the neighborhood info which is very useful for a home buyer. To spice it up, I have added Walkscore and Yelp review to make this a true one stop shopping experience!
Enjoy this for free and spread the word! As always, drop me a note if you have any suggestion for me.