Paid Twitter services coming by year's end

The company is developing tools and services that it might be able to offer on top of Twitter's free microblogging service, he said in a videotaped interview at a Reuters event.

"I think by the end of the year we'll have something out there," he said. " It doesn't have to be this super home run in terms of making billions of dollars. ... But it has to show a little bit of signs of life, telling folks, 'Yes Twitter can be a sustainable business.'"

The two year-old site has exploded in popularity this year but it's still unclear how exactly Twitter plans to make money

Stone said Twitter has hired a full-time product manager to analyze how it should develop paid services and suggested the company could sell "lightweight analytics" data to corporate users or perhaps a paid directory where it lists legitimate corporate Twitter accounts.

In March, Federated Media partnered with Twitter to launch a sponsored Web site called ExecTweets, which allows visitors to follow Twitter messages from executives in different industries.

But Stone said the company was thinking "less on the advertising front," telling Reuters that Twitter didn't want to hire the staff it would take to sell advertising.

Twitter is increasingly being used for corporate communications, where companies have found it an accessible way to immediately touch base with their customers. Companies like Dell and JetBlue have hundreds of thousands of followers on Twitter.

"The individuals are getting some kind of value out of these accounts," Stone said. "Companies are getting value out of these accounts."

Whatever the services turn out to be, the site will remain free and open to everyone, Stone added.