With the democratization of integration the number and types of people trying to share date between applications has grown considerably. In addition to developers, everyone from business analysts to power uses is trying to pull together disparate piece of data in order to highlight some greater truth.
Just in time for next week's mid-term US elections, just listed here is this API from The Institute on Money in State Politics. And in this case, it's the domain name that's more telling: followthemoney.org. It's quite an impressive store of data on the who, where, when and how much of campaign contributors across the US.