From the "NO KIDDING" Dept. :
The researchers found that the number of friends and wall posts (messages left by the owner of the profile or friends) that a person had on their profile correlated with how narcissistic they were. Study leader Laura Buffardi, a Ph.D. student in psychology, said this is similar to how narcissists behave in the real world, forming numerous but shallow
relationships with others.
Narcissistic Facebook users were also more likely to have glamorous, self-promoting pictures for their main profile photo, while others tended to use snapshots, the study found. The untrained observers also noted the differences in photos and amount of social interaction. "We found that people who are narcissistic use Facebook in a self-promoting way that can be identified by others," Buffardi said.