If you would like to begin to understand things like HTML, CSS, and PHP, these are some of my favorites.
HTML Goodies is a part of Earthweb. It is a friendly resource with lots of tips, tricks and advice on how to get the job done.
Web Monkey is a free, public resource for web developers. Builders, designers and programmers — the people who know best — write the articles, tutorials, code snippets and other contributions.
W3 Schools is a free web developer site full of web building tutorials.
Drupal is an open-source Content Management System well worth understanding in the web development realm!
jQuery is a JavaScript resource library with better browser compatibility.
HTML Kit offers a free service to convert image files into favicon.ico files.
Firebug is a is free and open source add-on for Firefox to help edit and debug web pages.