Great story yesterday on NPR on Caterina Fake, the CEO of Hunch.com. Fake was also recently featured in an article in WIRED. Hunch's 'decision engine' collects answers to seemingly random questions to help visitors answer their own queries. She states that the average number of questions answered is 120. That's an amazing level of contribution to the collection of data hunch has amassed--for free. And if participants don't give enough info in these 120 responses, the login is through Facebook or Twitter (although Twitter wasn't work when I just tried it.) I imagine that if you got an opportunity to ask someone you had never met 120 questions and poke through their Facebook page, you could infer quite a bit about someone's life!
In any case, it's a provocative business. I'm curious to learn more about their business model.