Time spent on social networking and casual gaming sites in June 2010 officially surpassed email according to an annual survey from Nielsen, with these top 3 activities accounting for 40% of all time spent online. Those in digital advertising sales and marketing take note.

Of the most heavily-used sectors, videos/movies was the only other to experience a significant growth, expanding by 12% from 3.5% to 3.9%. The number of videos streamed passed the 10 billion mark in June for the first time. The average American video viewer spent 3 hours 15 minutes streaming online video during the month.

See the chart below for details.  Source: Nielsen