IRIS provides seismic equipment and access to seismic and other data sets for researchers worldwide
Data: Overview of the Data Management Center holdings and access tools
Data Request Tools: List of tools for accessing seismic data.
Data Wizard: Not sure where to look for the data you want, or what kinds of data are available? The Data Wizard may help you.
SeismoArchives: Seismogram Archives of Significant Earthquakes of the World
