Medlane XMLMARC
Stanford University's Lane Medical Library details its experiment in using XML instead of MARC to organize its catalog data.

MARC Standards
Library of Congress Network Development and MARC Standards Office. Includes: general information, MARC documentation, MARC Advisory Committee, MARC SGML, records and systems, and software and utilities.

MARC Records, Systems, and Tools
Provides links to MARC vendors who market specialized tools that provide enhanced usability to MARC 21 records and systems. Includes both commercial and free tools.

UNIMARC
Universal Bibliographic Control and International MARC Core Programme (UBCIM). International Federation of Library Associations and Institutions.

Bibliographic Formats and Standards
An exhaustive guide to the MARC standard from OCLC.

Tag of the Month
A guide to most MARC cataloging tags with examples and text explaining their usage. Useful to persons needing plain descriptions of MARC fields. From Follett Software Company.

MARC.pm : Machine Readable Cataloging Perl Module
A free Perl module for processing MARC records.

Cataloging Cheat Sheet
A fast guide to cataloguing an item in MARC format. Provides a concise guide to abbreviations and field tags used. Really only meaningful to someone fairly familiar with MARC, but a useful cheat sheet.

MarcEdit
MarcEdit is a free windows based MARC editing tool, that provides methods for converting MARC to text, Text to MARC, MARC to XML and MARC to Dublin Core.

MARC 21 - MARC formats for the 21st century
"MARC 21 is the result of the activity undertaken to align CAN/MARC and USMARC. It represents the continuation of the CAN/MARC and USMARC formats in a single edition with a new name."

CAN/MARC home page
"The Canadian MARC Communication Formats serve as the common standard for the exchange of machine-readable authority, bibliographic, classification, and holdings data in Canada." Includes news and announcements, CAN/MARC documentation, MARC Records Distribution Service (MRDS).