A Dashing widget that tracks your progress toward unearned badges on Stack Overflow (http://stackoverflow.com/). It randomly selects a badge you haven't earned and shows your progress, or suggests things you could try in order to earn the badge. The widget's background colour dynamically changes depending on the badge's rank (bronze, silver, or gold).
The widget talks to the Stack Exchange API (https://api.stackexchange.com/) via the badgeoverflow-core gem (https://github.com/sharplet/badgeoverflow-core), which we wrote while developing the widget. The most significant part of this gem is the logic for calculating a user's progress toward a badge. We've implemented progress calculation for a large number of badges, and tried to make it as easy as possible to add more. For badges where we aren't (yet) calculating progress, we display the badge's description.