W3.org:

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

DOM 2 Views
AbstractView and DocumentView interfaces for accessing and updating a representation of a document.
http://www.w3.org/TR/DOM-Level-2-Views/
Top/Computers/Programming/Internet/W3C_DOM/Specifications

DOM 2 HTML
Builds on DOM 2 core, adding interfaces specific to HTML documents.
http://www.w3.org/TR/DOM-Level-2-HTML/
Top/Computers/Programming/Internet/W3C_DOM/Specifications

DOM 2 Events
Interfaces for mutation and user interface events. Allows a script to capture events, and includes support for event bubbling and cancellation.
http://www.w3.org/TR/DOM-Level-2-Events/
Top/Computers/Programming/Internet/W3C_DOM/Specifications

W3C Sample Code Library
A general-purpose Web API written in C
http://www.w3.org/Library/
Top/Computers/Programming/Languages/C/Libraries

Jigsaw
The official W3C Java-based Web server. (W3C is the WWW standards body.) With a modular architecture and full HTTP/1.1 compliance, the Jigsaw server is an experimental platform for W3C and the Internet community.[Open Source]
http://www.w3.org/Jigsaw/
Top/Computers/Programming/Languages/Java/Applications/Servers/WWW

SAC: The Simple API for CSS
Beta software for parsing CSS (Level 1, 2 or 3) stylesheets from the WWW Consortium (W3C). [Open Source, BSD-like]
http://www.w3.org/Style/CSS/SAC/
Top/Computers/Programming/Languages/Java/Class_Libraries/Data_Formats

Jigsaw Java Server
W3C's open source web server and servlet engine.
http://www.w3.org/Jigsaw/
Top/Computers/Programming/Languages/Java/Enterprise_Edition/JavaServer_Pages/Products/Engines

The XMLHttpRequest object
Specification by W3C, of the base of AJAX.
http://www.w3.org/TR/XMLHttpRequest/
Top/Computers/Programming/Languages/JavaScript/AJAX

Document Object Model (DOM) Level 1 Specification
Final W3C Recommendation for DOM Level 1. Defines core object model and features specific to HTML documents.
http://www.w3.org/TR/REC-DOM-Level-1/
Top/Computers/Programming/Languages/JavaScript/W3C_DOM/Standards_Documents

Document Object Model (DOM) Level 2 Specification
WORKING DRAFT for DOM Level 2. Work in progress. DOM 2 adds an event model, and an interface for setting style sheet properties.
http://www.w3.org/TR/DOM-Level-2-Core/
Top/Computers/Programming/Languages/JavaScript/W3C_DOM/Standards_Documents