The Biblio and OAI-PMH modules mantained by rjerome at Drupal.org have been updated with new releases.
This is exciting because there was no version of these modules for Drupal 6; they were already available for Drupal 5 but Drupal 6 has been out for almost a year now and is the best option for building new websites.
Biblio handles mantaining, displaying and exporting of bibliographic items that can be exposed via the OAI-PMH module. If you also throw in my Millennium Integration module, then you could import items from a library catalog straight into Biblio items. I say "could" because the current Drupal 6 version of Millennium Integration is stand-alone, that is, isn't tied to the Biblio module.
I will now start work on again integrating with Biblio to make Millennium Integration better.
Isn't Open Source great?