• by Laurie Sullivan  @lauriesullivan, August 2, 2010

What sucks Americans' time? Social networks top the list, followed by online gaming, according to a study released Monday by The Nielsen Co.

While social networks make some less productive, and others consider them the first source for news and information, Americans spent 43% more time on social networks in June, compared with the same month in the prior year. The 22.7% share of time spent on social networks ate into time spent on older technologies such as email and instant messaging. In fact, the uptick in social networks led to the 28% and 15% declines in email and instant messaging, respectively.

The research -- What Americans Do Online -- revealed that Americans spend 36% of their time communicating and networking across social networks, blogs, personal email and instant messaging. Nielsen conducted the study by monitoring daily surfing habits of 220,000 people in the U.S.

As social networks gain in popularity, so do online games. Social games like Zynga's FarmVille continue to benefit from the trend. The online game segment became the second most heavily used medium behind social networks, accounting for 10% of all U.S. Internet time.

In FarmVille, Washington state food producer Cascadian Farm struck it big when its organic blueberries began appearing in the game. More than 310 million C blueberry crops have been planted by more than 1 million people in the game. But try sending Farmer Joe Cascadian a "friend" request -- only to find Facebook believes he has too many.

Email, however, dropped from 11.5% of time spent to 8.3%; portals from 5.5% to 4.4%; and instant message from 4.7% to 4.0%. Despite the decline in time spent on email and IM, the study suggests predictions of their demise are premature.

Time spent on Web portals like Yahoo and AOL has declined, too. They represent 4.4% of Americans' time online, compared to 5.5% a year earlier. Mobile devices could give some hope for email and portals. The Nielsen study suggests that email remains the most popular activity on mobile phones. Americans spent 41.6% of their mobile online time on email, up from 37.4% a year earlier. Mobile phone users also spent more time on Web portals. Portals remain as the second heaviest activity on mobile Internet, with 11.6% share of time spent, despite the double-digit decline and social networking's rise to account for 10.5% share. This means the gap is much smaller than a year ago -- 14.3% versus 8.3%, respectively.

Music and video/movies are the other mobile Internet activities that have seen significant growth. Both have had more than 20% increases in share of activity year-over-year. As these destinations gain share, it's at the cost of other content consumption. Both news/current events and sports destinations saw more than a 20% drop in share of U.S. mobile Internet time.