This is one of the most useful examples of a data mash up that I have seen. It is a brillient piece of socially responsible publishing that lifts the lid on the relationships between US politics and money.
MAPLight.org says of itself “MAPLight.org, a groundbreaking public database, illuminates the connection between campaign donations and legislative votes in unprecedented ways. Elected officials collect large sums of money to run their campaigns, and they often pay back campaign contributors with special access and favorable laws. This common practice is contrary to the public interest, yet legal. MAPLight.org makes money/vote connections transparent, to help citizens hold their legislators accountable.”