"Our agents are able to work with a really high number of buyers" because of the efficiencies created by ZipRealty's online portals, said Lanny Baker, the company's president and CEO.

ZipRealty's agents also spend less time marketing themselves, he said, allowing them to serve twice the number of clients the average agent at a traditional brokerage has. That, in turn, gives ZipRealty's agents more experience, he said.

In about a month, USRealty.com is launching a new service that will allow do-it-yourself sellers to put their homes on a multiple-listing service, which will place the properties on the major home search websites without an up-front fee. Only when the home is purchased will the seller be charged by USRealty.com, according to Colby Sambrotto, the company's president and CEO.

The service, based in New York, will substantially reduce the cost of selling a home by eliminating a listing agent's commission, he said. (If the buyer is represented, a commission of that agent would still apply.)

"It really covers all of your bases from a marketing standpoint," Sambrotto said. "The big difference is you're showing the property yourself."

ForSaleByOwner.com is also trying to give buyers and sellers more options that the traditional commission structure, said Matt Brown, the company's business development director. For a $699 one-time fee, a homeowner can have their home listed on the multiple listing service and gain the online reach of a home listed by an agent, he said.

"We feel like we can do everything that an agent can do — at least as far as it's virtually concerned," said Brown of ForSaleByOwner.com, which is owned by the Tribune Co., the parent company of The Baltimore Sun.

Despite increased availability of online services that help people selling their homes themselves to get their properties on multiple lists, there still is an overwhelming preference among sellers to get professional help.

The National Association of Realtors says that last year about nine in 10 sellers used an agent, a rate that has been consistent for the last decade. The rate of buyers employing an agent to assist with the house hunt last year was also nine in 10, the association said.

Agents are most equipped to prepare a house for sale and price it so it sells in a short period of time for the most amount of money, said Dean Cottrill, president of Coldwell Banker Residential Brokerage's Greater Baltimore operations.

People often waste time trying to sell by themselves and are apt to get less than their home is worth, he said. Plus, even with the reach of a multiple-listing service, homes for sale by owner are not going to generate the interest of a home sold by a well-known firm, he said.

"There's no one who's going to find them more ready, willing and able buyers than we will," Cottrill said.

Buyers are more at ease pursuing a home that is being offered by a well-recognized brand, like Coldwell Banker, a 106-year-old company, he said.

Plus, agents are educated — all Maryland agents are required to take continuing education classes on topics including developments in real estate law — and create a buffer during negotiations that increases the buyer's and seller's comfort, Cottrill said.

After trying for at least a year to sell a Perry Hall Colonial himself, Len Sipes, a public affairs officer and social media manager for the federal government, contemplated paying a Web service to place the home on the region's multiple-listing service.

He set up a website to promote the home, put a video tour on YouTube and listed the home on Zillow.

"We were getting lots of hits … but we really were getting sporadic inquiries," he said. Recently, Sipes decided the online presence he set up wasn't working and that he needed expert help — and he signed a contract with a listing agent, he said.

"I'm as technically inclined as anybody," Sipes said. "It just wasn't working for us."