The New York Times has just announced its new Congress API, which provides capability for developers to access to four sets of data about US Congressional representatives and their votes: "a list of members for a given Congress and chamber, details of a specific roll-call vote, biographical and role information about a specific member of Congress, and a member’s most recent positions on roll-call votes" (see Congress API profile for details).
A few years ago, Tim Berners-Lee (inventor of the World Wide Web), urged his TED Talk audience to share raw, unstructured data in order to boost innovation and solve critical problems. The INOH API project aims to bring Berners-Lee's vision to light.
For music enthusiasts who thrive on insider knowledge and detailed music conversation, WhoSampled would be just their cup of tea. It's basically an online community for discovering and discussing sampled music, remixes and cover songs. WhoSampled has partnered with The Echo Nest to provide the WhoSampled API that allows developers to access and integrate its functionality with other applications.