NEW YORK — Tim Armstrong has looked like the unluckiest man in media for the past year. He used to be Google’s ad sales maestro, the definition of digital success. But ever since May 2009, when he took the job of turning around AOL, he has overseen abysmal earnings, wretched morale and a local news strategy that has been slammed as a money-losing Web sweatshop.

Then, in a move that not even the most gossipy of media obsessives saw coming, Armstrong announced at the Super Bowl in Texas that AOL was buying The Huffington Post, the Internet news darling, for $315 million. Armstrong went from looking lame to looking awfully sharp. And awfully lucky.

Perhaps no online property was lusted after by media moguls like the one Arianna Huffington founded six years ago. Its traffic rivals The New York Times. Its infrastructure is virtually zero-cost. Its social media strategy is practically perfect. Oh, and it turned its first profit last year on $30 million in revenue.

HuffPo expects to triple revenue by 2012. “The Huffington Post was in big-time growth mode, and in theory this gives them access to the resources they’ll need for even faster growth,” said Andy Chapman, the head of digital trading at MindShare North America, a unit of the ad agency WPP PLC.

Huffington’'s original vision was to create the political left'’s answer to the right-leaning Drudge Report, minus the venom. Huffington leveraged her personality and her access to the elite’s dinner-party circuit to lure 250 celebrities —"creative minds,"” as she called them,— to blog about topics from business to the boudoir.

These were the earliest days of social media. At the time, seasoned media executives were scared to death of opening up their sites to the madding crowds. Journalism was a heavily filtered, one-way broadcast.

Huffington somehow saw around the social-media corner. She persuaded everyone from Walter Cronkite to Diane Keaton to blog. For a paycheck of zero. The model was laughably low-cost. To this day, the home page still looks decidedly low-budget and cluttered.

Early on, Huffington’'s brainchild was also roundly panned.

One early critic, New York University journalism professor Jay Rosen, said at the time, "“Barry Diller doesn’t have time to hunt down juicy links for his readers."” But Rosen’'s take turned out to be wildly wrong.

Huffington'’s writers were heavyweights — and because readers could chime in, she immediately garnered a loyal audience of insatiable news addicts.

Huffington sensed, perhaps more than anyone, that readers didn’t just want to share news. They wanted to share it, comment on it and then put it up on their Facebook pages and Twitter accounts. It wasn’t long before HuffPo started serving as its audience’s curator.

Editors scoured the Web for the most scintillating content and then repackaged it on the site. Huffington also understood that on the Web, linking and being linked to is what makes traffic growth steroidal.

But by aggregating other news providers’ content, sites like The Huffington Post, critics say, are poisoning the news revenue model and threatening the Fourth Estate along the way. Last year, former Washington Post Editor Len Downie Jr. referred to news aggregation sites like The Huffington Post as “parasites living off journalism produced by others.”

The Wall Street Journal’s editor-in-chief, Robert Thomson, drew a more specific comparison: “Tech tapeworms.”

Huffington'’s site now gets 25 million unique visitors a month, rivaling The New York Times’ 32 million. AOL can use all the help it can get. The company is widely viewed as a dial-up dog, a relic of the days of the ever-present “You’ve got mail” voice.

Of late, its media strategy has seemed schizophrenic. In buying The Huffington Post, AOL is also buying Arianna, who will assume the role of editorial content overlord. For the first time in its history, the company will have an executive who understands how online content works.