Hunch (acquired by eBay)

Hunch helps you make and discover great recommendations. Hunch's ambitious mission is to build a “Taste Graph” of the entire web, connecting every person on the web with their affinity for anything, from books to electronic gadgets to fashion or vacation spots. The Taste Graph already contains more than 500 million people, 200 million possible recommendations, and 30 billion correlations, giving Hunch the ability to make accurate predictions for just about anyone or anything.