Social networking has overtaken e-mail as the most popular Internet activity, according to a new study released by Nielsen.

The reach of social networking and blogging venues is growing at twice the rate of other large drivers of Internet use such as portals, e-mail and search.

Nielsen found that two-thirds of the world's Internet users visited a social networking site in 2008.

All told, social media now accounts for almost 10 percent of Internet time.