Thanks. The professor was aware of IRIS, but I'll tell his student about your link just in case. Roger, I don't know anything about ISC: I just heard them talking about paying about $150 (academic discount?) and said I would post here.
For other data, the NGDC is free for a lot of things: we downloaded an 8 gig tar file of multibeam bathymetry, which unstuffed to 1300 files and 17 gigabytes. This is the largest file that I have ever downloaded.

Chris