Developed during last month's Facebook Global Hackathon Finals, PolitEcho is a browser plugin (available on Chrome, for now) intended to help you better understand what kind of political bubble you exist in. Facebook itself already predicts your political preferences, but that intel is private and only visible to you and (surprise! ) advertisers. PolitEcho brings that info to the forefront so you can see who in your social circle skews politically left or right.
Here's how it works
PolitEcho discreetly scans all of your Facebook friends' profiles and takes note of all the outright political pages a person has liked. Then it looks at all of the other pages they like -- say, the New York Times, or The Onion, or Thrillist -- and compares them against a database of sites that have been rated for a liberal or conservative bias. Finally, it assigns each person a total numerical "score" and plots them on a graph somewhere between very liberal to very conservative.
Hovering over each dot on the graph reveals which friend of yours it represents, and provides a list of the sites that person liked that factored into their score. It'll also let you know how confident PolitEcho is in its prediction, assigning it a "low," "moderate," or "high" confidence rating. Keep in mind that if your friend has their privacy settings set to "only me" under "who can see the people, pages, and lists I follow," they won't be included in the graph.