By Elizabeth Razzi
Sunday, June 17, 2007; F05

What if the object of your affection suddenly became available? And what if it were swept away by another suitor before you even learned that news? It would be a tragedy, right?

If that object is a home, there's a way to position yourself as a well-mannered stalker ready to pounce as soon as that coveted place, or any house in your favorite neighborhood, comes on the market.

The Web site Trulia.com allows you to set a "Trulia Alert" for any address in its national database, even if it is not listed for sale, and to receive an e-mail if that house goes on the market or if nearby properties are listed for sale or sold.

Trulia is one of the brash upstarts in the online real estate world. The site launched in September 2005 and added Washington area properties in July. Last month, it was the 32nd-most-visited among 2,640 real estate sites, according to Hitwise.com, which compiles usage statistics.

The alert feature was added to the site a bit more than a month ago, and it just might be the site's most interesting and useful feature. But there's nothing on the site that shows you where to find this feature or how to use it.

All you have to do is enter the address in the main "Find Homes For Sale" box , even if it is not for sale. You won't necessarily get a lot of information. When I tried it for my own address, all I found was a basic Google map and some incomplete and out-of-date tax-assessment information. But now that I've set an alert, I'll be able to keep tabs on the neighborhood, at least if listing brokers feed their information to Trulia.

The alerts would be useful if I did have a home for sale. It's good to know quickly that someone a few blocks away just listed a similar house for $10,000 less than your asking price; that's going to affect how many buyers look at yours. It's a real estate agent's job to pass that information to you promptly, of course, but it doesn't hurt to set up an alert as a backup. And anyone trying a for-sale-by-owner can certainly use the automated help.

If you're shopping for a home, you definitely want to keep tabs on new listings and sales. You have more bargaining ammunition once a similar home comes on the market, especially if it's listed at a lower price than the home you had been considering.

The entry for my house on rival Zillow.com was more robust than Trulia's entry, even before I updated the Zillow information myself. Trulia does not invite homeowners to update their home's information, as Zillow does, but there is a "Report Listing Error" button.

Most similar real estate sites make a living by capturing your contact information and re-selling it as a sales "lead" to real estate brokerages. Such sites tease you with a bit of information and then require you to supply your name, phone number and e-mail address to learn more.

Trulia does not force you to jump through such hoops. It doesn't sell your contact information to anyone but instead earns revenue from advertisements and "featured listings," which receive more prominent display than the regular, free listings.

Listings appear on Trulia only if the listing broker chooses to put them there.

The site gets 1.5 million users a month nationwide, Trulia spokeswoman Heather Fernandez said. If you're interviewing real estate agents before listing your home for sale, ask them if they plan to put your home on the site or on any others. Some agents like to keep a tight hold on where their listings are posted online, but it's probably to your advantage that the listing be posted as broadly as possible, and Trulia doesn't cost your agent any money. The site does not accept listings for properties listed for sale by owner.

Listings show full addresses, unlike the listings on Realtor.com, the official Web site of the National Association of Realtors and the most-visited real estate site, according to Hitwise. I gave Trulia a workout searching for homes for sale in the Shouse Village neighborhood adjacent to Wolf Trap in Vienna. It's a well-kept neighborhood with a lot of split-level houses built in the 1970s. I zeroed in on a five-bedroom house on Tuba Court listed at $899,000.

The site said it has been on the market more than 30 days. That's handy information, but it would be much more useful to know precisely how long it has been on the market. A long listing time can indicate that the sellers haven't been willing to lower the price enough to get the house sold. In fact, the home was pulled from the market, unsold, a few days ago. When I asked the listing agent, Richard Ganley of Long & Foster, about the listing, he was unaware that it had been posted on Trulia. "Never heard of it," Ganley said.

One of Trulia's calling cards is that, once you find an appealing home, you can see loads of statistics for that home as well as comparisons with nearby homes. You can get quarterly statistics and charts for that Zip code showing average listing prices, average sales prices, median sales prices, average price per square foot, and the number of sales. You can compare the price per square foot of the house with that other houses that have sold recently.

I found the plethora of data mind-numbing. There is no analysis, and if I were considering buying a home, I would have to tune it all out and focus on the condition of the bathroom tiles, the view from the kitchen window and the traffic during rush hour.

Trulia also offers a list of comparable homes on the market along with those that have sold recently. That's a useful feature but only if you already know enough about the neighborhood to pick the real comparables out of the list. For example, I signed up to receive e-mail alerts about houses similar to the one on Tuba Court. Among them was a notice about a five-bedroom house on Towlston Road in Great Falls on 2.76 acres, for sale at just less than $2.2 million. As the crow flies, it's nearby, but it's a world away in terms of dollars.

E-mail Elizabeth Razzi atrazzie@washpost.com.