CNet's Builder.com - HTML - You can freely read any of the articles on this site. But to fully participate you need to register for free.
HTML Goodies by Dr. Joe Burns
Lissa Explains It All - Very basic explanations of HTML written for children but just as good for adults.
Annabella's HTML Help
A Beginner's Guide to HTML
HTML Clinic
AAA HTML - Step by Step Guide and Tutorials by Email