The Open Source Digital Library System (OSDLS, a.k.a. Powerful Yet TactfullyHelpful Electronic Arranger of Sources (PYTHEAS)) is a project to develop an open source next-generation library system. Current development includes a data model based on MARC and RDF expressed in XML. Links to the design draft and listserv details are at the OSDLS homepage.
MARC.pm is a Perl 5 module for reading, manipulating and writing MARC records. Once installed in your Perl library you will be able to use MARC.pm's functionality to read in individual records or batches of MARC records, extract data from particular fields, and convert the records into a variety of formats including HTML and XML. You can also use MARC.pm to create records from scratch--which might prove useful if you have have some delimited data that you would like to convert into a MARC record. Since it is a Perl Module, MARC.pm might prove also prove to be useful as a component of a larger application that uses MARC in some form.
Stuart writes: "M[n]M is software that
supports processing of national standard MARC MeSH subject authority records for use in medical library online public access catalogs. While designed for use with Innopac M[n]M can also be used to manage MARC MeSH in other OPACs. M[n]M is freely available under the GNU Public License. To download M[n]M or to read more, go to library.med.nyu.edu/mm".
There's also a very informative paper describing M[n]M available here.
seen on many lists recently is XMLMARC, a "Java client/server program [which] converts MARC to XML based on flexible maps and simplified, yet detailed DTDs for bibliographic and authorities formats." Its license is free for non-commercial use but requires consent for redistribution, and their broader experiment is described here. They seem to be aware of MARC.pm... it would be great to see a side-by-side feature comparison of the two.