Nicko from the Sunlight Foundation sez,
Today the Sunlight Foundation launched Inbox Influence, a tool for Gmail that instantly shows you the political giving and lobbying history of the people and organizations mentioned in emails you receive. The easy-to-use tool can be used as a first step in researching influence background on corporate correspondence, adding context to newspaper headlines or discovering whom is behind political fundraising solicitations.
Inbox Influence works by tapping into Influence Explorer, Sunlight’s library of federal and state data of political contributions, lobbying records and more. It provides details on any identified entity in the body of the email, plus information on both the sender of the email and the company from which it was sent. With it, you can even see how your friends and family have given to political campaigns.
Inbox Influence | Influence Explorer
(Thanks, Nicko!)