Memorial University Libraries' Cataloguer's Toolbox - A comprehensive list of web resources related to cataloging, including MARC documentation, LoC Cataloging tools, Bibliographic utilities, Conferences, and Blogs & Wikis.
The RDA Blog - Salman Haider's RDA Blog brings together resources (links and descriptions), news and developments, and explanations of RDA cataloging standards. Entries are tagged and users can explore by category. Particularly useful is the "RDA Resources" page, which links a variety of web resources on RDA, including training materials.
OCLC Bibliographic Formats and Standards, 4th Edition. This page is a guide to cataloging in OCLC's WorldCat. Though it is in the process of being revised, the guide provides catalogers with the standards and guidelines for entering records into WorldCat, including guidelines for cataloging special formats such as theses and supplements. The page also links to OCLC's RDA resources.
Library of Congress Subject Headings, via Linked Data Service. Search LC Subject Headings. Includes variants, use for, broader terms, narrower terms, related terms, LC Classification (Call number), and Alternate formats. From the LC Linked Data Service, users can also search the LC Authority files, LC Children's subject headings, LC Genre/Form Terms, etc.
MARC Standards from the Library of Congress. Plenty of information on MARC, including tutorials on "Understanding MARC Bibliographic," "Understanding MARC Authority," and "Understanding MARC Holdings Records," as well as an Introduction to MARC, guide to MARC documentation, Record requirements, guide to coding electronic resources in a MARC record, and more.
Library Cataloguing Aids compiled by Lynne LeGrow. LeGrow, Cataloger at Halifax Public Libraries in Nova Scotia, Canada, has compiled this helpful comprehensive list of cataloging resources from around the web. LeGrow has divided the resources into categories, which include AACR2, Authority Work, MARC, RDA, and Library of Congress Subject Headings, among others.
025.431: The Dewey Blog is "everything you ever wanted to know about the Dewey Decimal Classification System but were afraid to ask." The blog features news, tips, special/editorial topics, and explanations on DDC topics. The blog's contributors are primarily OCLC's Dewey editorial team.
Library of Congress Authorities - From the Library of Congress, users can search, browse, and view the authority headings (Subject, Title, Name, Title, and Name/Title, and also by Keyword) and also download MARC authority records for local use. Search results include the full MARC display.