arstechnica writes about opensecret.org:

“ […] Center for Responsive Politics […] runs OpenSecrets.org to provide a clearing house of data on political contributions and lobbying efforts, with the hope that bringing some transparency to the inner workings of the political system will lead to a more informed citizenry.

[…]

Apparently, behind the scenes, the group has developed a process for importing the data from these disparate sources and placing it in a structured database […] under the Creative Commons Attribution Non-Commercial Share Alike license.

[…]

What the data may provide that’s new, however, is the ability to identify broad patterns in the data that aren’t apparent by looking at the information that can be obtained from any one source, or by focusing on a single campaign. Although the name of OpenSecrets.org suggests a focus on individual disclosures, it’s possible that, by opening its data to the public, the group will enable researchers to develop a clearer sense of the big picture of money and politics.”

Here are the APIs: http://www.opensecrets.org/action/apis.php