In the last few days, a new Web site launched with great fanfare but spotty performance. When CNN included a story about it on their evening news, the site couldn’t keep up with the hits. Why all the fuss? Zillow promises to give homebuyers and sellers up to date and complete information about the value of their home and comparables in their area. Some have suggested this will make real estate agents obsolete because people will be able to price their own homes to be competitive. The early returns are that the site’s information is incomplete and sometimes wrong, which makes the suggested price ranges they give hard to justify. In some cases, the range is optimistically high, and for others, I’ve negotiated sales higher than their top amount. The site depends on public records for its data. But public records will not show factors, like recent additions and improvements or the condition of the interior, that affect price. Public records can also be wrong; a friend of mine checked her h...