The controversy over the Internal Revenue Service's handling of applications for non-profit status from Tea Party groups has put a spotlight on a subject with which we at the Sunlight Foundation Reporting Group are all too painfully familiar: The migraine-producing complexity of the nation's campaign finance system. To shed some light on the ongoing debate, we've decided to share what we know. As often is the case with systems worthy of Rube Goldberg, it's easier to draw than to describe.