Contents:
(Items in BOLD are most recommended)

 

Introductions and Tutorials
Intermediate Guides
Quick References
Web Accessibility
Style Guides
Tables
Frames
Forms and CGI Sripts
HTML Tools
Checking your HTML work
Other HTML Information Indexes

INTRODUCTIONS & TUTORIALS
A Beginner's Guide to HTML
This is absolutely the first place you should start, even if you're using HTML editor software. I think it's a good idea for you to understand what the HTML tags and options mean. Some editors use them in inappropriate ways. This document is also nice because you can view it online in pieces or print out the entire document.
A Beginner's Guide to URLs
So, you want to make a Web Page!
HTML tutorial from Joe Barta
Introduction to HTML - by Eric A. Meyer
Introduction to HTML - by Ian Graham
How to write HTML files

 

INTERMEDIATE GUIDES
Intermediate HTML
Netscape Extensions to HTML 2.0
Netscape Extensions to HTML 3.0
Hagan's HTML Help Library
This may not be available for long, so read it while you can.
How do they do that with HTML?
An easy to read guide to the most common questions.

 

QUICK REFERENCES
Guide to HTML Commands
Very comprehensive index, split up in multiple pages
D. J. Quad's Ultimate Tag Reference List
Less comprehensive but easier to navigate
HTML Quick Reference Guide
Not quite as comprehensive, but it's all on one page. This is probably better if you're not exactly sure what you're looking for. Much more of a "quick guide."
Quick Guide to HTML Tags
A four page guide that's a good introduction to tables and special characters.
Bare Bones Guide to HTML
HTML Documentation
Otmar's List of HTML tags
HTML Quick Reference
Special Characters
HTML Special Characters: iso8859-1 (Latin-1) table

 

WEB ACCESSIBILITY

Making sure your pages are accessible to those with disabilities

 

Accessible Web Page Design - in English & French
Contains a list of design issues and how each is handles by various special browsers.
Accessibility Issues on the Web
A very comlete list of suggestions for designing accessible web sites. There is less discussion of the problems that can occur if you don't follow these guidelines.
Designing Accessible Websites
This is a list of links for further research on this issue.
Unified Web Site Accessibility Guidelines
This is a very comprehensive document containing methods to diagnose and correct common accessibility problems.
WebABLE
The authoritative Web directory for disability-related internet resources. Contains the latest news, websites, conference listings, and a very large library of articles, white papers, projects, and online journals.
World Wide Web Consortium's (W3C) Disabilities Developments
This site contains the latest news and research about accessibility issues on the WWW.
Web Access Symbol Now Available
This image may be freely used by webmasters to denote that their site contains accessibility features to accommodate the needs of disabled users.
Writing Accessible HTML Documents
A list of design guidelines, each with reasoning, implementation details, and results before and after the change.

 

STYLE GUIDES
Creating Killer Web Sites
David Siegel has some really interesting ideas about web design. It's worth a read, even if you don't agree with him. The section on browser offset is particularly useful.
Tips for Writers and Designers
Same guy (Daivd Siegel) - more ideas
Dmitry's Design Lab
Contains very well-written monthly articles about effective web design from the graphic design perspective.
Yale C/AIM Web Style Guide
An HTML Style Sheet
Directed toward commercial and large information sites.
Web Developer's Virtual Library: Style
Web Pages That Suck
Learn good design by looking at bad design. Basically, this site is a Web design course based on learning from others' mistakes. This page teaches with bad examples the don'ts of Web publishing.
HTML Bad Style Page
Top Ten Ways To Tell If You Have A Sucky Home Page
Sucky to Savvy
This is the follow-up to the above top-ten list. It includes techniques for avoiding common problems. Both these sites are well worth a visit.
Making the Most of the World Wide Web for Your Organization
Style Guide for Online Hypertext
Composing Good HTML

 

TABLES

See also: HTML Tools, further down the page

Table Tutor
Tables in Netscape
Design Ideas for HTML Tables
The problems with tables
The HTML3 Table Model
Very advanced -- read this after you really understand tables.

 

FRAMES
Frames Tutor
The Art of Frames
Frames: An Introduction - Netscape
Targeting Windows
Useful in conjunction with Frames
THE Netscape Frames Tutorial™

 

FORMS & CGI SCRIPTS
Form Tutor
CGI Manual of Style
The CGI Resource Index
An amazing resource. Includes programs and scripts, documentation, books, articles, programmers and job openings.
Matt's CGI-Script Archive
Mosaic for X version 2.0 Fill-Out Form Support
Decoding FORMs with CGI

 

HTML TOOLS
FrameShop
TableMaker
The Table Sampler
HTML Tools from the University of Colorado, Boulder

 

HTML VALIDATION
Why Validate Your HTML
A Kinder, Gentler HTML Validator
Checks your HTML code for errors general errors based on document type.
Doctor HTML
This tool checks for different types of errors, including document, table, and form structure, spelling errors, image size and specification, loading time, and link viability. I am completely amazed by this online resource.
Web Site Garage
The "Tune Up" area checks any URL you enter for various problems including load time, link viability, spelling errors, search engine ranking, and HTML design. It's got a very different layout, and analyzes aspects of your site that many other validation tools don't. It also has a "GIF Lube" area where you can reduce the sizes of images via GIF and JPEG compressions.
Bobby--Web Site Accessibility Verifier from CAST
This validator allows you to check compatibility with lots of different browsers (older and newer versions). It also checks to see whether your page is accessible to those with disabilities.
NetMechanic
This site contains 2 tools, one for checking HTML code for errors, based on browser compliance, and the other checks external links for errors. Nice features of this site include the ability to run jobs in the background and have it e-mail you when complete and the ability to search a page or an entire site.
WebTechs HTML Validation Service

 

OTHER HTML INFORMATION INDICES
Webreference.com
An incredible resource for design and programming.
The Art of HTML
Nicely laid-out, includes reviews of HTML pages.
The Web Designer
Web Mastery Resource Lists
Help sites, broken down by topic.
HTML Documentation
Yahoo - HTML
Yahoo - Page Design and Layout