Gravity uses Interest Graph for Web Personalization.
Adam Rifkin stashed this in Interest Graph!
Gravity used partner websites to get massive distribution:
Currently delivering more than 25 million personalized content recommendations per day to more than 200 million users. The startup is working with more than a dozen large publisher clients, including The Wall Street Journal, TIME, CNN Money, BUZZMEDIA, and TechCrunch, with others to be revealed soon.
The average piece of personalized content gets recommended to 8 people.
Not sure how that math works out.
Next up, they're launching an ad exchange: "A lot of media and content companies are looking for smarter ways to monetize their audience in more authentic and effective ways, which means moving beyond banners."