ExoAPI is an ongoing project that extends the accessibility of exoplanetary data by providing an easy to use RESTful API. ExoAPI was created during the NASA Space Apps Challenge by a team of three amazing geniuses who knew nothing about space before they started this...and still don't really.
Currently the data is provided by http://exoplanetology.blogspot.com/ who in turn feeds the data from http://exoplanet.eu/. The ExoAPI team plans on extending the API to encompass a wider array of data sources and more interesting space data to reach as many programmers as possible and encourage an explosion of space data based mashups.
See ExoAPI.com for more info