in reply to Automated MARC data retrieval
databases you might search with NET::Z3950
get a list from here
finding book data: Net::Amazon might help
I do recoment Koha (www.koha.org) : last time I checked it was written in Perl, used HTML::Template, could import MARC records, and, most important, it was used in real life ... the only drawback was that it was overkill for the research library I worked for ...