Thokbook
Personal library system using Perl, PostgreSQL , YAZ .
You only need record ISBNs; it looks up book info on the Internet.
GLibrary
MARC.pm : Machine Readable Cataloging Perl Module
MARC 21 Concise Format for Bibliographic Data
The YAZ Toolkit
oss4lib -- Open Source Systems for Libraries
Koha - Open Source Library System
library management software Toolkit
Seul/Edu Library Applications