W3.org:

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

SVG Test Suite
Official W3C test suite for SVG 1.0. Includes downloads for test suite and harnesses, link to test results for six SVG implementations, and email feedback link.
http://www.w3.org/Graphics/SVG/WG/wiki/Test_Suite_Overview
Top/Computers/Data_Formats/Graphics/Vector/SVG

Amaya
W3C's experimental browser with built-in SVG viewer and editor [Open Source]
http://www.w3.org/Amaya/
Top/Computers/Data_Formats/Graphics/Vector/SVG/Software

Vector Markup Language (VML) Submission to W3C
Vector Markup Language (VML) World Wide Web Consortium Note 13-May-1998 - Submission to the World Wide Web Consortium.
http://www.w3.org/TR/NOTE-VML
Top/Computers/Data_Formats/Graphics/Vector/VML

W3C Overview of WebCGM
News and description about WebCGM, a profile of CGM, specifically designed for use on the Web. It adds hyperlinking, hotspots, and HTML integration to the existing graphical facilities.
http://www.w3.org/Graphics/WebCGM/
Top/Computers/Data_Formats/Graphics/Vector/WebCGM

W3C WebCGM specification
The WebCGM specification, now a W3C Recommendation and becoming widely implemented for industrial and technical graphics on the Web, intranets and extranets.
http://www.w3.org/TR/REC-WebCGM/
Top/Computers/Data_Formats/Graphics/Vector/WebCGM

Getting Started with HTML
Headings, paragraphs, text emphasis, links, images, lists, tables, and also cascading style sheets.
http://www.w3.org/MarkUp/Guide/
Top/Computers/Data_Formats/Markup_Languages/HTML/FAQs,_Help,_and_Tutorials/Beginners

W3C HTML Home Page
Full information on HTML and links to all the specifications.
http://www.w3.org/MarkUp/
Top/Computers/Data_Formats/Markup_Languages/HTML/Reference

HTML DTD
Required and optional parts of the HTML document type definition.
http://w3.org/MarkUp/html-spec/L2Pindex.html
Top/Computers/Data_Formats/Markup_Languages/HTML/Reference/Cheat_Sheets

HTML 4.01 Specification
HTML specifications set by the W3C.
http://www.w3.org/TR/REC-html40/
Top/Computers/Data_Formats/Markup_Languages/HTML/Reference/Specifications

Hypertext Markup Language - 2.0
A detailed list of HTML tags.
http://www.w3.org/MarkUp/html-spec/html-spec_toc.html
Top/Computers/Data_Formats/Markup_Languages/HTML/Reference/Specifications