Stumble it! 
I would like to highlight this piece of research done by Danah Boyd, a doctoral student at University of California-Berkely, about friends, ‘friending’ and social networks.
Unfortunately and clearly, you can see (she also mentioned it) that the sample size was only limited to US based youths. Apart from highlighting the rather worrying online idiosyncrasies of US pre-teens, this paper gives you another perspective about the definition of ‘friend’ and puts that in context with social networks such as Myspace and Friendster.
“As a kid, you used your birthday party guest list as leverage on the playground. ‘If you let me play I’ll invite you to my birthday party.’ Then, as you grew up and got your own phone, it was all about someone being on your speed dial. Well today it’s the MySpace Top 8. It’s the new dangling carrot for gaining superficial acceptance. Taking someone off your Top 8 is your new passive aggressive power play when someone pisses you off.”
“When people first joined Friendster, they took cues from the people who invited them. Three specific subcultures dominated the early adopters — bloggers, attendees of the Burning Man [14] festival, and gay men mostly living in New York.”
