An average American Facebook user spends 7 hours a month on the site

"The average U.S. Internet user spends more time on Facebook than on Google, Yahoo, YouTube, Microsoft, Wikipedia, and Amazon combined. Think about that for a moment.
New numbers released by Nielsen today confirm what we’ve known for a while: Facebook is the web’s #1 time sink. What’s more interesting though is just how much more time we spend on the world’s largest social network today than we did 6 months ago.
Back in June 2009, Nielsen estimated that the average U.S. user spent 4 hours and 39 minutes on Facebook per month. That’s about 9.3 minutes per day in a 30 day month. In August, that number rose to 5 hours and 46 minutes, or 11.5 minutes per day.
In January 2010 though, the amount of time the average person spent on Facebook jumped to over 7 hours. Each American Facebook user spent an average of 421 minutes on Facebook per month, which amounts to over 14 minutes per day. Even if you lump together the time spent on Google (1:23), Yahoo (2:09), YouTube (1:02), Microsoft/Bing (1:35) Wikipedia (0:15), and Amazon (0:22), it still doesn’t beat Facebook."
Source: Nielsen, reported by Mashable, 16th February 2010