"There are 550,000+ apps that are used on Facebook. Seventy percent of users engage with apps each month. There are one million app developers. Zynga, the top app developer, made $250 million in 2009. Of that amount, $80-$150 million is estimated to be profit, more net profit than Facebook itself made."
"There are 1,500,000 active Facebook pages. The average value per fan is $136.38. Extrapolating on that, many celebrity pages would be worth enormous sums:
Michael Jackson, with 13.3 million fans, would have a page worth $1.8 billion. Family Guy has 9.5 million fans for a worth of $1.3 billion. Lady Gaga and Barack Obama each have 9.1 million fans, worth $1.2 billion each. Vin Diesel has nine million fans, worth $1.1 billion. Starbucks has 8.2 million fans, worth $1.1 billion. South Park has 6.2 million fans for a worth of $845 million."
I would love to see something similar for the Android and Apple app store economies.