With many thousands of RSS feeds available on the Web, you're never going to be able to keep up with everything, nor would you want to: not all the stories on your favorite feed will always interest you. Ensembli is an online feed reader, with a twist–instead of picking the feeds you want, you tell it the topics you're interested in. It searches across all the feeds it covers (currently only 1,200 but the company is adding more and you can request specific feeds) for that topic, but rather than just returning the most recent stories, it tries to show you the most relevant. At first, it does that by collaborative filtering and using agents that predict what you’ll be interested in based on other, similar users. But as you read, ignore, mark as favorites, and delete different stories, Ensembli creates a personal profile for you and uses that as the basis for what stories it sends you. The info it collects includes whether you favor or dislike certain sites, whether you look at shorter or longer pieces, whether you always look at newer stories and delete old ones to clear the page out, and which particular topics you look at in your results. It is all about your behavior.