The company: Rose Associates, an 80-year-old real estate marketing and management company based in New York City. Rose has 200 employees and manages some 20,000 luxury apartment units.

The idea: Bob Scaglion, Rose's senior managing director of residential marketing, uses Twitter's search function for lead generation, which works well, because people often send messages about apartment hunting travails. "Our clientele is young and upwardly mobile," he says. "Twitter is where they are." The easiest way to find customers who are looking for what you sell is to go to and start typing in keywords. Rose uses 10 key terms, like New York City apartments, moving to New York City, and no fee rentals. When a person uses one of these phrases, someone in the company's marketing department sends a reply message like the one above with a link to Rose's apartment listings. Unsolicited messages from strangers might sound creepy, but such is life on Twitter.

The result: No followers? No problem! Rose has only 200 followers on its Twitter account but generates 100 leads a month by sending a few targeted replies every day. Scaglion says roughly half of those leads convert to actual rentals, which is pretty good, given that the program costs almost nothing.

How to find leads faster: There are dozens of Twitter applications that can continuously search Twitter and alert you when a keyword is used. Scaglion's company uses an application called TweetDeck and a Web service called DemandSpot, both of which are free.