As time goes on I suppose I will write some articles on the topic. For now here is my annotated list of web authoring resources.
Joe Barta's Tutorials The tutorial I learned from. Excellent for the beginner and as a reference for anyone. Perhaps the most comprehensive set of tutorials online. Printed and membership based features as well.
W3C the World Wide Web Consortium. The site for technical information pertaining to HTML.
HTML Help has much more readable information than W3C. As well as a very informative FAQ.
Jukka Korpela has many articles concerning HTML and web design, often delving into very detailed explanations. He has also written Learning HTML 3.2 by Examples which takes more of a 'text book' approach than some tutorials, i.e. it is thorough without a lot of fluff.
Apache Documentation Many times an author has a question that is easily accessible in the server documentation. Of course this is only one possible server that you might be hosted on.
Good Practices has numerous articles on the varying topics related to good site design. Mostly well written articles by noted web authors concerning their opinion of site design.
Yale Style Manual some info was a little dated last time I checked but the article makes some good suggestions. Especially, for the newcomer to web authoring.
An article on White Space Bugs by E. Stephen Mack, although last updated 1997 many of the 'bugs' still occur and plague web authors.
Caching Tutorial discusses the various caches that are a concern in web authoring. And what an author can do to use these to his advantage as much as possible.
Viewable with Any Browser is a noteworthy campaign that I support and any web author should consider.
Please note that viewable is the operative word. While browsers you did not design for specifically may lose some formatting or nice features, they should still get the main content.
MediaBuilder has many online utilities for creating and editing graphics and a graphics library.
Still using a MAILTO Form? Stop it! Now go here and get yourself Remotely Hosted Form Processing.
Response-O-Matic is a nice remotely hosted form-to-mail processor. Very minimal advertising.
Newbies Beware: The Mythical Mailto an article taking a closer look at why mailto fails when used for HTML Forms.
W3C's Validator validate your HTML against one of several DTDs in typical w3c robustness. If you find the error messages difficult to understand try one of the other sites listed.
The WDG's Validator provides more meaningful error messages.
Page Valet is based on the WDG Validator but offers other features.
A Real Validator is a program available for Windows that gives the same level of accuracy as the online validators mentioned above.