How much is your home sweet home worth? Zaio -- short for Zone Appraisal and Imaging Operations -- aims to provide instant access (through its Web site) to property information on almost every residential property in the 250 largest US cities. Its proprietary GeoScore property rating system uses comprehensive property data including real estate appraisals and property photos provided by contracted independent appraisers and photographers to calculate an estimated valuation. Revenues are generated by selling geographic zones to appraisers and photographers and property information to customers including mortgage companies, county tax assessors, investors, and property owners.