Online map shows housing hot spots

One huge Web success story for house buyers and real estate searchers has been Seattle-based Zillow.

A San Francisco-based realty-search competitor, Trulia.com, is also worth checking out.

One of Trulia’s highly visual elements is a “heat map” system that displays listing prices for homes in any one region; highest prices are displayed in brighter red colors while lower prices fade off toward the green spectrum.

The heat map is a true mash-up — a site that pairs up multiple listing service data with maps to produce a hybrid set of information tailored to the specific interest of home sales.

What Trulia uses in its heat maps are the listed prices for a region, state or county. That choice produces some curious results. If you produce a heat map for Washington state, the counties with the highest — brightest — heat spots are the usual counties like King and Snohomish, but also Okanogan and Kittitas.

The reason is the decision to use listed price, not sales price. It’s likely that in both countries there are some very large farms or ranches on the market, skewing the results.

The Trulia heat map pages also include, right below the maps, a database showing the actual numbers used to generate the colored display. That data can be sorted by either listed price or by median sales price in that county.

Kitsap County, which ranks fourth in “listed price,” falls to 36th in the state when sorted just for median sales price (covering completed transactions).

Okanagon which was fifth in the listed price ranking, fell to 29th in median sales price.

Still, Trulia offers a different take on the real estate market. It’s a worthwhile way to watch the real estate Web.