BiblioteQ - Open Source Catalog Software and Library Management Suite

http://biblioteq.sourceforge.net/index.html
from the website it says:

"BiblioteQ strives to be a complete and thorough library management suite. The application is supported on numerous platforms, including FreeBSD, Linux, OS X, Solaris and Windows. Installers are available for OS X and Windows.

For some categories, BiblioteQ provides a mechanism for querying the Library of Congress, or any other Z39.50-capable system, via the standard Z39.50 protocol; thus simplifying the data-entry process.

As for database support, BiblioteQ allows for connectivity to both PostgreSQL and SQLite database engines. "

Will give this a whirl.