While Pepaj, Waters and Halpern have gained global audiences via Twitter, other businesses have found it useful to cement relationships with local regulars.

At least two mobile food services, Green Truck To Go and Kogi Korean BBQ, use Twitter to let customers know when and where their food trucks will be in their neighborhoods.

In less than a year, Kogi has developed a cult following among tech-savvy L.A. clubgoers and other night owls, and was used as a case study by Houston market research firm MarketingProfs. The study, which surveyed 200 business users, said Twitter ranks behind only blogs as the social media tool delivering the most value.

Has its limits

Green Truck, a Culver City catering company offering healthy fast food at film shoots, workplaces and special events, initially put GPS trackers on its vehicles so customers could track the trucks on its Web site, said General Manager Bobby Allen.

But the trackers often malfunctioned and it switched to Twitter feeds. Being able to inform customers exactly where a truck is parked has been a boon, but Allen admits that Twitter has its limits in expanding his customer base given that Green Truck's typical clients are older than Kogi's.

"When you see both us and Kogi at the same location, most of their customers are reading tweets on their cell phones while waiting in line; ours less so," he said. "We've considering some Twitter-only promotions just to measure how much businesses we actually get from it."

San Francisco-based Twitter last month announced it would release analytical tools to help businesses more precisely measure the service's effectiveness by the end of the year.

The venture-backed company, which turned down a $500 million bid from Facebook last year, is struggling to devise a revenue stream that won't turn off its growing user base.

So far, executives are promising to keep Twitter updates free, and ban advertising and usage charges, but most likely will charge for the add-on business tools.