Sure, but I would think that knowing what people are searching for is more valuable. Also, based on a quick scan on alexa.com, the top 100 (global) sites are a

Sure, but I would think that knowing what people are searching for is more valuable. Also, based on a quick scan on alexa.com, the top 100 (global) sites are a mix of search engines, social networks, news and porn sites. I doubt the search engines and social networks will adopt the like button and I'm not sure how much you learn about someone's interests based on the news they read and porn they watch. Maybe they'll partner up with Microsoft and monitor your searches on Bing. I think they already show results from Bing when you search on Facebook.