CISTI Document Delivery (Canadian Institute for Scientific and Technical Information)
http://cisti-icist.nrc-cnrc.gc.ca/docdel/docdel_e.shtml

GeoRef (American Geological Institute)
http://www.agiweb.org/georef/dds.html

Michigan Information Transfer Source (MITS)
http://www.lib.umich.edu/mits/