One idea that I've thrown around, and seen out there, is the ability to send in a polygonal area that I want to search in and have the API return the houses for

One idea that I've thrown around, and seen out there, is the ability to send in a polygonal area that I want to search in and have the API return the houses for sale/rent in that area. Letting the user pick the neighborhood or even the side of the street they want to live on is really powerful. The funny thing is, I've called one of the major geolocation providers and asked for something along these lines and they couldn't provide it. Built it myself in under 24 hours using open source geo-encoding tools and Google Maps.