W3.org:

W3.org has 287 URLs listed in 163 Dmoz categories.

Official CSS1 Test Suite from the W3C
Provided as a way for vendors and page authors to test their browser's conformance to the CSS1 specification.
http://www.w3.org/Style/CSS/Test/
Top/Computers/Data_Formats/Style_Sheets/CSS/Tools/Browser_Testing

Associating Style Sheets with XML documents Version 1.0
W3C specification that allows a style sheet to be associated with an XML document by including one or more processing instructions with a target of xml-stylesheet in the document's prolog. (W3C Recommendation 29 June 1999)
http://www.w3.org/TR/xml-stylesheet/
Top/Computers/Data_Formats/Style_Sheets/CSS/Using_with_XML

W3C - Security Resources
Information systems security resources, including crytography, digital signatures, and protocols / standards.
http://www.w3.org/Security/
Top/Computers/Education/Certification/CISSP

How to Add a Favicon to your Site
Draft article from the W3C, giving details of how to associate an icon with a web page.
http://www.w3.org/2005/10/howto-favicon
Top/Computers/Graphics/Web/Favicons

World Wide Web Consortium
International industry consortium founded in 1994 whose purpose is to develop specifications, guidelines, software, and tools to promote the Internet's evolution and ensure its interoperability.
http://www.w3.org/
Top/Computers/Internet

Inaccessibility of CAPTCHA
A W3C Working Group Note explaining how CAPTCHAs can present a major obstacle to users who have limited vision or a learning disability such as dyslexia. This document examines a number of potential solutions and alternative systems.
http://www.w3.org/TR/turingtest/
Top/Computers/Internet/Abuse/CAPTCHA

Tim Berners-Lee
His official site at W3C includes biographies, information about his book, and questions and answers about his contributions to the internet.
http://www.w3.org/People/Berners-Lee/
Top/Computers/Internet/History/People/Berners-Lee,_Tim

A Little History of the World Wide Web
A hyperlinked timeline from 1945 to 1995, with references, from The World Wide Web Consortium.
http://www.w3.org/History.html
Top/Computers/Internet/History/Timelines

W3C RSS 1.0 News Feed Creation How-To
Guide offers a simple way of creating RSS 1.0 news feeds from one's W3C related domain, activity or working group home page.
http://www.w3.org/2001/10/glance/doc/howto
Top/Computers/Internet/On_the_Web/Syndication_and_Feeds/RSS

W3C RDF Validation Service
A full RDF Validation Service - for use with any RDF, not just RSS 1.0
http://www.w3.org/RDF/Validator/
Top/Computers/Internet/On_the_Web/Syndication_and_Feeds/RSS/Validators