Quick, what is your House of Representatives district? Many people don't know this number, or the member who represents them. The New York Times' new Districts API makes it easy for your application to answer the question for any point within New York City, though it could serve as a template for a nationwide--or even international--service.
Election time in the U.S. has political parties thinking about connecting with voters. Before an app can help encourage civic engagement, it needs to know where the voter lives and to which districts their location corresponds. The Districts API returns not just House data, but also City Council, the State Assembly and State Senate. No more sending users to a separate site to figure out their districts, at least within New York City.
This sort of simple data is the glue that could hold together a whole new generation of political mashups. The Washington Post's voting history API comes to mind as one ripe for mashing with this new service from NYTimes. The Districts announcement post also points to other mashup-ready APIs and its own NYC landmarks example (see who represents Yankee Stadium in the image above).
If the last several elections in the U.S. were about embracing the web's social tools, the next few may be about APIs and data sharing to help voters get the information they need to make their decisions in the booth. Sunlight Labs has been an innovator in this space in many ways, including its Congress Android app, with information about every House representative.