The study showed that people in 2009 on average spent 42% of their time online on content sites compared to 34% in 2003, when the OPA launched its Internet Activity Index, which tracks monthly Internet use across five categories: commerce, communications, community, content and search.

The actual amount of time spent on content sites has nearly doubled since 2003, increasing from an average of three hours, 42 minutes to 6:58.

By contrast, people are not lingering as long on communication-focused properties, which include Web sites and services such as Yahoo Mail, AOL Instant Messenger and MSN Groups. People spent only 27% of their time on communication sites in 2009, down from 46% in 2003. Time spent fell 8% from 5:20 to 4:54.

The share of time spent on commerce sites fell less dramatically, from 16% to 13%, while the actual time actually increased 26% from 2:07 to 2:40. A major factor eating away at time spent on communication and commerce sites has been the rise of social networking sites in the last few years. The OPA only added the "community" category last year to reflect that phenomenon.

"In 2008, we introduced the Community category based on the emergence and popularity of sites like Facebook, MySpace and LinkedIn," said OPA President Pam Horan in a statement. "These new sites have had significant impact on the communications category, which saw a 41% decline, due to the fact consumers are using community sites where they can conduct these same activities more efficiently."

Today, community sites account for 13% of Internet users' time, and 3:01 on average per person each month. Time spent with search, meanwhile, has doubled from 27 minutes to 54 minutes, but its share of time has grown only from 3% to 5%.