Protocols

RFC Sourcebook - Description of protocols, file formats, glossary of terms, RFCs.
http://www.networksorcery.com/enp/

XNS.org - Independent organization managing the eXtensible Name Service, an open protocol and open-source platform for universal addressing, automated data exchange, and privacy control. Includes an overview, charter, history, and specifications.
http://www.xns.org/

Free Protocols Foundation - Independent public forum supporting patent-free protocols. Includes policies, papers, a mission statement, and a list of free protocols.
http://www.freeprotocols.org/

Internet Encyclopedia - Overview of Internet protocols.
http://www.freesoft.org/CIE/Topics/73.htm

Internet protocols - General comments on protocol design, and good reference material on a few protocols (especially mail-related; also ftp, time, and misc) by Dan Bernstein.
ftp://koobera.math.uic.edu/www/proto.html

The Kermit Project - A protocol that transfers text and binary files without errors between diverse types of computers over potentially hostile communication links, and a suite of communications software programs; Columbia University.
http://www.columbia.edu/kermit/

Internet2 - A consortium led by universities working in partnership with industry and government to develop and deploy advanced network applications and technologies, accelerating the creation of tomorrow's Internet.
http://internet2.edu/

Port Numbers and Services Database - Well known port numbers for TCP and UDP, from Internet Assigned Numbers Authority (IANA).
http://www.sockets.com/services.htm

IETF Internet Drafts - List of documents organized by alphabetized subjects.
http://www.ietf.org/1id-abstracts.html

Active IETF Working Groups - A directory of the Internet Engineering Task Force groups and their web pages.
http://www.ietf.org/html.charters/wg-dir.html