“It seemed pretty accurate,” he said. “I also used it to check what price the home was last sold for. I didn’t want to offer much more than what the previous owner bought it for a year or two ago.” Carpenter, 28, still checks his and friends’ houses on the site every few weeks – and he sees why so many have become addicted to Zillow. “It’s personal information that people won’t openly share, and it’s posted on the Internet,” he said. “I think everyone has a little bit of a voyeuristic mind.” Some real estate agents however, are not thrilled with Zillow, saying it often gives buyers and sellers flawed information. Detroit area Realtor Rick Dulai said the site has led some of his clients astray. “It’s a starting point for a conversation,” he said. “But you should still talk to an agent or an assessor and be ready to accept that Zillow could easily be 10 (percent) to 20 percent off.” The creators of the travel Web site Expedia.com founded Zillow in February 2006. Both sites held the same goal of making information widely available that was once the realm of travel agents and, in Zillow’s case, Realtors and public records. Zillow pulls its information from many of the same sources real estate professionals do, but the site applies its own methodology to determine the “Zestimate.” “There is this real hunger for real estate information and it wasn’t easily available for free,” said Zillow spokeswoman Amy Bohutinsky. “The value of our homes is something we talk about at neighborhood barbecues … now Zillow fuels that conversation even more.” The site, which lists nearly 70 million homes nationwide, has built a significant following, Bohutinsky said. The typical visitor spends 10 minutes on the site, respectable by Web standards, and a half-million people have submitted information on their homes to improve Zillow’s records. Homeowners and agents can freely list homes for sale on Zillow. The site’s only revenue comes from advertising. A growing number of Zillow followers have named their “Make Me Move” prices. That feature allows a Zillower whose house is not on the market to set a walk-away price. The feature is popular in areas such as San Francisco, where potential buyers can’t find homes in the neighborhood they want to live, Bohutinsky said. The popularity of “Make Me Move” and other quirky features (such as Zillowing the neighborhoods that were home to the TV shows “The O.C.” or “Knots Landing”) proves that the site is used for entertainment as well as research. The site does not openly list celebrity homes, you must have the address to look up the value. No names are assigned to the property. Another concern with Zillow is accuracy of the home values it lists. The site’s accuracy is determined by the difference between a house’s Zestimate and what it actually fetches once it’s sold. Zillow claims its national median error is about 7.2 percent, which means a home the site listed for $100,000 typically sells for between $92,800 and $107,200. Like all assessments, Zillow tends to be most accurate in neighborhoods of largely similar homes. Bohutinsky said the site is still a work in progress. “We still consider ourselves a beta site,” she said. “We’re gathering more information every day … we’re really starting to bloom now.” MARGIN FOR ERROR The site’s accuracy is determined by the difference between a house’s Zestimate and what it actually fetches once it’s sold. Zillow claims its national median error is about 7.2 percent, which means a home the site listed for $100,000 typically sells for between $92,800 and $107,200. 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! Some use it to get the scoop on their neighbors. Others use it to keep an eye on the value of their own homes. Still others use it to get a better price on their dream house. No matter the reason, millions of Americans are Zillowing. At a time when home prices in some areas of the country are slipping, Internet browsers are turning to Web sites such as www.zillow.com to check out their homes and others. Launched just a year ago, Seattle-based Zillow has broken from the pack of Web sites that allow surfers to enter a property’s address and obtain its estimated value. Zillow has received national attention, and last month captured 4 million visitors – adding 400,000 users in February alone. Generally aimed at those looking to buy or sell a home, Zillow often fascinates users for hours as they check values of neighbors’ homes, price houses in upscale enclaves and of local celebrities – or grit their teeth as they see whether their own homes’ values have increased or decreased in the past month. Zillow uses public assessments, sales of comparable homes and publicly available information on the property to derive its “Zestimates.” Homeowners can click onto the site and add specific information, such as a new deck or remodeled kitchen, to get a more accurate Zestimate. But critics complain that the estimates aren’t always accurate, and don’t even exist for thousands of homes. In communities where it does work, though, Zillow is gaining converts. Ben Carpenter became a fan of the site as he hunted for houses recently. He said Zillow information allowed him to purchase a new home in Berkley, Mich., last month for less than the asking price. He said he checked 15 homes on the site before visiting each.