ranked aggregation
robhyndman.com: "but also because ranked aggregation is kind of a holy grail in Web 2.0 right now - everyone is trying to figure out how to replace the human editor and make aggregation of quality content scalable."
Social aggregation is another obvious candidate (let your friends help you find the good stuff). What you find interesting is different from what I find interesting, so ranking things by amount of comments, incoming links and such can only be part of the picture.
# Feb 5, 2006