The company you keep...

..determines what you buy. Check out this study about how social network connections can predict purchasing patterns. It's a really interesting idea and can help refine target marketing if harnessed by MySpace, Facebook or other social networks. It makes sense that people with common interests would also tend to buy the same stuff. The study was not able to prove whether these people actually discussed the products or if they were more likely to buy simply because they were similar to each other. I think it just furthers the argument for word of mouth type efforts.