The top two Twitter trending entertainment topics in the first half of 2011 were singer Rebecca Black and Femme Fatale, the recent album from Britney Spears, while UK band Mumford & Sons were the eighth most popular topic.

And four of the top five Twitter users based on number of followers are musicians, with Lady GaGa and Justin Bieber at one and two, ahead of Barack Obama.

Meanwhile, Eminem's official Facebook page has the third largest number of "likes", according ...