I saw my own Interest Graph and it's scary-accurate. We'd certainly pay for the ability to use the Gravity personalization technology I saw today at TechCrunch to help target content to users.

Gravity is ambitious. Its technology is a potential threat, or an opportunity, depending on how you see it, to the ad platforms at both Google and Facebook. It's also one of the most interesting machine learning and data mining experiments I've seen.

Gravity's team of engineers uses semantic technology to analyze and parse the social-data usage patterns of individuals to get an idea of who they are and what interests them. That information could be highly coveted by marketers and advertisers.