Tutorials and Resources

Sitepoint
W3 Schools
Web Developers Virtual Library
Mozilla Tutorials
O'Reilly Tutorials
Eclipse downloads

X/HTML

WDVL - HTML Tutorial
WDVL - XHTML Tutorial
Sitepoint - HTML & XHTML Tutorials
W3 Schools - HTML
W3 Schools - XHTML

CSS

W3C - Learning CSS
W3 Schools - CSS
Sitepoint - CSS Tutorials
WDVL - CSS

Javascript

Firebug overview - the author, Joe Hewitt - YUI Theater
Firebug tutorial - Jim Plush
Firebug tutorial - Jesse Newland
Firebug tutorial - digitalmediaminute
Client-Side Javascript Reference - Sun Microsystems
JSEclipse download - Adobe Labs

DOM

DOM Tutorials - O'Reilly
Gecko DOM Reference - Mozilla

Perl

The Camel Book
CGI.pm

Servlets/JSP

Apache Tomcat
Apache Tomcat API
Jakarta/ ASF
JBoss Application Server
J2EE 1.4 API
JSE 5 (1.5) API
Servlet API
JavaServer Pages API
JavaServer Pages Standard Tag Library
Spring Framework

Ruby

Official Ruby Home Page
Ruby @ Wikipedia
Ruby Central
Programming Ruby (online textbook)
Ruby News - O'Reilly
RubyForge
RAA - Ruby Application Archive
Ruby-Doc.org

Rails

http://www.rubyonrails.com/
37Signals
37Signals at Wikipedia

AJAX

iframe Tutorial & Examples
W3Schools - iframe
W3Schools - AJAX

Standards

W3C
ECMA
Internet RFC/STD/FYI/BCP Archives

X/HTTP

HTML 4.01
XHTML 1.0
W3C - Markup Validation Service

CSS

W3C - CSS Specifications
W3C - CSS Home Page
W3C - CSS Validation Service

JavaScript

ECMA-262: ECMAScript Language Specification

DOM

Document Object Model (DOM) - W3C

XML

XML-W3C - Home page
XML 1.0 (Fourth Edition) - W3C

Cookies

IETF - RFC 2965

Java

JSRs: Java Specification Requests
JSR 154: Java Servlet 2.4 Specification
JSR 245: JavaServer Pages 2.1

Ruby

Ruby Standard Documentation