The API for the Incorporated Research Institutions for Seismology’s (IRIS) Seismographs in Schools Program returns XML. It retrieves stations, station information, events, event information, and networks affiliated with IRIS.
Founded in 1984, IRIS is a consortium of the over 100 US universities that have research programs in Seismology. It is funded by the National Science Foundation to distribute seismic data for free.
Its education program, of which the API is a tool, is extensive and aimed at helping educators teach seismology. Aspects of the program include showing educators how to monitor earthquakes in real time, hosting workshops, providing paid summer internships for earth science undergraduates, and providing publications on the topic. Within each of these areas are subdivided topics and activities. For example, within "Teaching About Earthquakes," there are "Teachable Moments" comprising presentations on recent earthquakes, animations to teach concepts, video lectures and lessons ready for presentation.
IRIS also has tools for researchers from archived data to a "Data Wizard" which helps researchers figure out where to find the data they are searching for.
Material available is right up to the minute. For example, in the teachable moments section, IRIS features a blog entry on a 7.4 magnitude quake off the shores of Guatemala, that occurred on November 7.