from freshmeat: "This is a small example application using the DigitalConvergence Cat: Optical Reader. The application allows you to scan the ISBN barcode of a book and retrieve its information from the Library of Congress. Optionally, this data can be stored in a local database table." Download the perl code here [1]. Hmm, doing z39.50 by hand it seems...
Links:
[1] http://www.ftope.com/barcode/CatALog-0.01.tar.gz