Apartments from dozens of real estate firms and websites with information about more than 1,000 apartment buildings are available here, amounting to more than 200,000 units. This is not a multiple listing service, according to company president David Levy, but focuses on the consumer.

"It's a mirror image of a multiple listing service," he says. "An MLS is a data base of properties that a broker or buyer searches directly. What we've created is a data base of buyers, in addition to a data base of properties, so a broker can find prequalified and active buyers."

Apartment hunters reportedly provide information about how big a unit they are looking for, when they plan to move, etc. They can select from among the buildings where they would like to live and be alerted about availabilities. There is no fee for brokers to list an apartment, but www.cityrealty.com co-brokers listings and is compensated if it secures a buyer.