An anonymous reader writes "Weighing in on Yahoo's recent acquisition of Tumblr for $1.1 billion, social networking entrepreneur Adam Rifkin argues that Tumblr is extremely valuable business property because it has successfully organized itself around the 'Interest Graph' (people interested in the same hobbies or things), rather than the 'Social Graph' (family, friends, and coworkers/colleagues, as is typical for Facebook). He opines that, for a social networking site, readers are far more important than writers; writers, after all, 'have time but no money. Certain groups are going to be overrepresented: Students, stay-at-home moms, the underemployed, retirees.' While readers are just the opposite: they 'have money but no time.... They want to see a picture of a watch they like, and buy it now.' In other words, it's the readers of the content that businesses are trying to reach. And interest graphs can be specifically targeted by businesses, much more so than social graphs."