Opensecrets.org - Money in Politics Data

Description

'Your Guide to Money in US Elections'. Includes databases covering money spent on:

• 527s
• Contributions
• Lobbying
• PACs
• Travel

Also has a 'revolving door' database:

Track the movements of well-connected individuals between government and private interests in this searchable database of more than 6,400 people. See which influential lobbyists and firms have ties to the offices and agencies they lobby. Learn which government agencies have sent the most employees into the more lucrative private sector."

Openness

• Access: no automated way to download all data but can search direct from their databases page (and can probably spider this way).
• License: none specified but general nature of site would indicate freedom to use, reuse and redistribute (though they do have a paid-for custom data service).