Before there was a Google Maps API, Adrian Holovaty created Chicago Crime to show updated crime data by location. Holovaty's lessons were later put into play in the Knight Foundation-funded EveryBlock, now owned by MSNBC. And now, EveryBlock has an API.
The announcement post warns that the API contains a serious amount of data, so is best left to serious developers:
This is a "firehose" API that delivers up to 24 hours of news items across our 16 cities. Since we deal with a diversity of news that vary in kind and format from city to city, this API is intended to serve partners with heavy-duty needs and who can devote a goodly amount of development time to work with the data.
A lighter-weight alternative to the API is the EveryBlock widget. The widget allows you to configure simple copy-paste code to embed relevant local news on your Web site.
Since the site was originally launched to help get this hyperlocal information to the people, an API is a natural evolution. One stumbling block, perhaps, for developers, is that not every city has the same types of data. For example, Dallas does not have 911 calls. To handle the differences, EveryBlock has published schemas to describe the types of data available in each city.
EveryBlock is currently in 16 cities across the United States. It follows the model of Chicago Crime by aggregating publicly-available data, such as emergency calls. It also identifies local news and blog posts. Outside.in has a similar concept, more focused on the news portion, and relaunched its API in September.