MapLight looks at the connection between campaign donations and legislative votes in an effort to reveal money's influence on politics.
MapLight performs research on supporting and opposing interests for legislative bills. MapLight's Bill Positions API provides a tool for discovering the connection between campaign donations and legislative votes. It can also be mashed up with other databases that contain information about bills or politically-active organizations. This RESTful API returns results in JSON or XML.
Just in time for the next election season, the team at MAPLight.org offer the MAPLight.org API which enables developers to "illuminate the connection" between money and politics by providing detailed funding information for candidates for political office.