Americans spend over 900 hundred million hours on social networks and blogs per month, 43 percent more time than they did last year, according to Nielsen. As you can tell from all the Zynga coverage, online gaming is another qu

ickly growing category, rising in total usage time by 10 percent year-over-year. In fact, online gaming overtook email -- which dropped several percentage points in use -- to become the second most heavily used category.

More than one-third of internet time is spent on social networks, blogs, personal email and instant messaging services.

“Despite the almost unlimited nature of what you can do on the web, 40 percent of U.S. online time is spent on just three activities – social networking, playing games and emailing leaving a whole lot of other sectors fighting for a declining share of the online pie,” said Nielsen analyst Dave Martin.

It would be nice if Nielsen were to stop putting social networking sites and blogs together in the same category. This categorization made sense a few years ago, but now the two are so totally different that it’s time to separate them, as it confuses the results of studies like these.

While Web 2.0 rules the fixed web, Web 1 is the king of the mobile internet. Almost half of mobile internet time is spent emailing (twenty-five minutes out of a total hour), and social networks and blogs are accessed only a quarter of this time, just a little over six minutes per hour.

Here are some of Nielsen’s other findings:

• Of the most heavily-used sectors, videos/movies was the only other to experience a significant growth in share of U.S. activity online. Its share of activity grew relatively by 12 percent from 3.5 to 3.9 percent. June 2010 was a major milestone for U.S. online video as the number of videos streamed passed the 10 billion mark. The average American consumer streaming online video spent 3 hours 15 minutes doing so during the month.

• Despite some predictions otherwise, the rise of social networking hasn’t pushed email and instant messaging into obscurity just yet. Although both saw double-digit declines in share of time, email remains as the third heaviest activity online (8.3 percent share of time) while instant messaging is fifth, accounting for four percent of Americans online time.

• Although the major portals also experienced a double digit decline in share, they remained as the fourth heaviest activity, accounting for 4.4 percent of U.S. time online.

By Mark Alvarez