It was a strange sight in Harvard Square—a tree outside of Peet’s Coffee had four vouchers for free burgers and fries from b.good taped to it.

Seconds later, b.good CEO and co-founder Jon J. Olinto updated the company’s Twitter account “b_good_” with a cellphone picture and an invitation for its 151 Twitter followers to come claim the vouchers.

Twitter, a three-year-old microblogging service, has millions of users who post steady streams of short updates called “tweets” that are limited to 140 characters. Twitter’s user base swelled 900% last year.

Companies, in turn, are quickly catching onto the service as a marketing tool.

“There’s so much opportunity to have dialogue with people in a very authentic way. That’s the cool thing about Twitter,” Olinto said. “Most companies have to speak in press releases...[but Twitter] allows you to be yourself.”

LET’S GET PERSONALIZED

Twitter’s form of communication can provide uniquely personalized dialogue with customers. On April 1, a disgruntled Boloco customer tweeted the chain’s account, writing, “True story: There was tin foil in my soy smoothie today. It was not delicious.”

Within hours, CEO and co-founder John Pepper tweeted back under username “boloco”: “hi there, sorry about that. foil not part of recipe. [Direct message] me your boloco card #... thanks!” Pepper’s 840 followers also saw the tweet.

But the communication between CEO and customer is not always about resolving ill will. When one Boloco fanatic tweeted about “annihilating my previous ‘# of burritos in a week’ record,” Pepper invited him to message him for free burritos to continue his winning streak.

“I don’t look at it like marketing. I look at it as dialogue,” he said. “It’s sort of a natural extension of what I should be doing anyway. This is a more efficient way to do it.”

Oggi’s Gourmet in the Holyoke Center, a restaurant that specializes in pizza, has a Twitter account run primarily by its co-founders Steve R. Welch and Bill Warner under the username “oggigourmet.”

“The marketing tool that Twitter gave us was to be able to say less tailored things, talking in slang to students, and they would accept it more,” Welch said.

The Harvard Book Store also keeps a Twitter at “harvardbooks” of events and updates written in a friendly, casual tone.

Diana G. Kimball ’09, a Twitter user with a passion for the Internet, agreed with the importance of humanizing a company through Twittering.

“You can’t just use it as a advertising platform,” she said. “I really have to feel like there’s a person behind it.”

THE PERKS OF BEING A TWEETER

B.good’s twitter runs special promotions, including playing Twitter hide-and-seek with burger vouchers around Boston.

Over the weekend, Olinto offered free sweet potato fries from 11 p.m. to 2 a.m. on Friday at its Harvard Square location. He found the number of people who responded to the experiment—thirty—somewhat disappointing, but will continue to roll out promotions.

Eric C. Chen ’11 is a b.good follower who was already a customer when he discovered the chain’s account.

“I like the fact that this is a local restaurant trying to reach out to us,” he said, adding that he would check out future promotions.

Oggi’s Welch has also run promotions, but out of 180 followers, only two came in over the course of a two-hour slot to claim their free slice of pizza with code word “London broil.”

Oggi’s, which markets itself more to Square professionals, has seen an increase in interest from student customers as a result of its recent use of Twitter, according to Welch.

Customers have also come in to the restaurant to chat after following his posts on the Web site, he said.

While Welch and his co-owner both tweet, he said that they sometimes hands over the task to the store’s public relations representative when they are too busy.

But the business ramifications of using Twitter as an advertising vehicle are still unclear.

“Honestly, I can’t say that we’ve had any more business through Twitter than any other advertising,” he said. “Twitter can be effective if you have many, many followers and they’re in tune to your company.”

And although the service has provided a valuable new mode of informal communication, Welch said it is not going to replace their traditional print advertising anytime soon.

The plus side?

“It doesn’t cost us anything to tweet,” he said.

—Staff writer Lingbo Li can be reached at lingboli@fas.harvard.edu.