Technology has drastically changed the way homes are bought and sold. In the old days, prospective home buyers relied on all-knowing real estate agents to guide them through the knotty house-hunting process, alerting them to open houses, telling them about local schools and helping them figure out if they could afford certain neighborhoods.

Now all that information is at consumers fingertips. Home buyers with just a little tech savvy can go online with Zillow.com or Trulia.com to scout out houses from their PCs or even their mobile phones. Indeed, most prospective buyers do their initial shopping online: Nearly nine out of 10 recent buyers use the web in their home search, according to the National Association of Realtors (NAR). And on the sales side, more real estate agents are utilizing social media sites like Facebook, Twitter and their own blogs to market properties, the NAR says.

As a result, more and more digital services are popping up, promising to help consumers find their dream homes. While Trulia.com and Zillow.com have three million to four million unique visitors a month, according to Compete.com, there are places on the web with just a few hundred thousand users that house hunters would nevertheless do well to check out.

SmartMoney asked real estate industry professionals which lesser-known web sites and services home buyers should use to guide them through the bumpy real estate market. Here are four that stood out:

Listingbook.com

Listingbook partners with powerful local Multiple Listing Service databases to provide an interactive community for agents, buyers and sellers. Valerie Van Cleef, associate broker at Coach Realty in Long Island, thinks of it as a beefed-up version of the traditional MLS. Account holders set their search parameters and the site automatically updates those property listings as soon as they re uploaded into the MLS database. Users can browse local listings, track open houses, edit their preferences and communicate with their broker. Other listing sites offer similar information, but since Listingbook pulls its data from MLS s, it s going to be the freshest, the pros say. You ll be the first to know if a new house that matches your search criteria becomes available, says Van Cleef. "It s definitely the most tech-savvy search and communication tool out there," she says.

However, consumers can only set up an account through a broker and Listingbook.com is not available in every state yet. But getting an account through a specific broker doesn t mean you must work exclusively with them.

Doorfly.com

Finding a good real estate agent is the first step in the buying process. That's where Doorfly.com comes in. Through the site's bidding system, home buyers anonymously submit their needs -- neighborhood, maximum price, size -- to a pool of real estate agents. Based on that criteria, agents compete with one another over prospective home buyers -- and offer an incentive rebate from their commission at closing. Buyers can compare offerings and select one they think best fits their needs. The rebates vary significantly based on the bidding agent, the cost of the home the buyer is looking for, and even the location, says a company spokesman. Agents have offered rebates ranging from $200 to $6,500.

Given the potential price break, soliciting a bid for their business is a good starting point for home buyers, says Sid Davis, a real estate broker in Farmington, Utah. Just keep in mind, he says, that working with a savvy agent can save you more than what you might reap with a rebate.

Market Snapshot

If you re a real estate junkie and a data junkie, get ready to wipe the drool from your chin. Market Snapshot, which is tucked away on Realtor.com s home page, lets buyers and sellers stay on top of market trends. "It gives buyers and sellers a really good look at what s going on in the local marketplace -- if it s worth it to sell their home, should they stay, should they buy at this price," says Joelle Senter, general manager at Keller Williams-Fox Valley Realty in St. Charles, Ill.

Users enter their home address to request a report and within 15 to 90 minutes they receive the first one. (Reports are free and keep coming until you cancel your subscription.) Each report contains average ask and sale prices for the designated neighborhood, inventory levels, how actual sale prices compare with listing prices, the average time houses spend on the market -- all presented in whiz-bang graphic displays. And because the program takes its data from multiple listing services, which track homes currently on the market, it's continuously updated.

Walkscore.com

Looking for a new home in an unfamiliar neighborhood can be daunting. The process, though, can be made a bit easier with WalkScore, a tool that measures the "walkability" of neighborhoods in the U.S., Canada and Britain. Users type in a street address and the site produces a list of nearby stores, libraries, movie theaters, parks, schools and restaurants and determines the area s so-called walkability rating.

"This is part of that old location, location, location saying," says Matt Dollinger, an agent trainer at @properties in Chicago. Even more important than the number of bathrooms or backyard space a house has, buyers want to get a feel for the neighborhood and whether it s conducive to their life changes over the next few years, he says.