Great map from the boys and girls at www.flowtown.com.
As you can see Facebook is bigger than most countries 🙂 It also seems to remind me of the shape of China?
Also not sure too much on Google Buzz. What is its niche? And what is HABBO?
“Social media are media for social interaction, using highly accessible and scalable publishing techniques. Social media uses web-based technologies to turn communication into interactive dialogues.” Wiki