I believe you are referring to Zillow.com, which provides an aerial
view of the neighborhood and the value of homes which have recently
sold in the area. Please be aware that Zillow is not available in all
areas of the United States as of yet. In many cases, an aerial view of
the neighborhood is available but market data might not be compiled.
Coverage areas for Zillow
"The home data we have compiled to generate a Zestimate home
valuation varies by location. Some counties provide all the data we
could hope for, but others are lacking such key things as the number
of bedrooms and bathrooms, or, in some cases, the square footage of
the home. The more data we have, the more accurate the Zestimate."
"To measure the accuracy of the Zestimates, we've gone back in time
and compared the historic Zestimates with the actual transaction
prices of homes that sold. The tables below are a measure of that
accuracy. They also show you where we have the greatest amount of
data, or little data. (Sometimes we have no data, in which case there
is no Zestimate.)"
Map and Search
You might find the following article of interest:
"Zillow unveils real-time home values service - Online startup's tool
will estimate worth of properties," by John Cook.
I trust this is the site you are seeking. Let me know if I can
clarify anything further for you.