Online Tools

AnyBrowser - Offers a screen size test, meta tags, html validation and link check.
TinyUrl - Make a long url short.
W3c - An excellent resource for web design, includes html & css validator. A must!
Tizag Tutorials - Teaches beginner web programmers how to use HTML and CSS.
Net Mechanic - A great site with some free tools to help improve your site.
Bare Bones - Lists all html tags that current browsers are likely to recognize.
Html Clinic - HTML tutorials with lots of examples you can follow and learn from.
Html Goodies - Offers extensive tutorials on tags, programming, basics & scripts.
WebXact - Tests for quality, accessibility & privacy issues.
WDG - Great online tools I use this or html and link validation.
Dynamic Drive - Free DHTML scripts and components to enhance your web site!
Javascript Source - Excellent JavaScript resource with tons of "cut and paste" scripts.

Css

Web Standards - Complete guide to Css.
Real World Style - Css layout, tips & techniques.
Css Play - One of my favourites on css!
Tanfa - Css design style.
Cbel Style Sheets - 195 css-related sites.
Css Vault - Everything you need to know about css!
Zen Garden - Displays the beauty of css.
Css Max Design - Step by step tutorials using css.
Css Html Dog - Everything HTML and CSS, used in making web pages.
Nick Rigby - Web standard techniques and resources, for beginners and experts alike.

Publishing Tools

Free Web Submission - Free site submission.
Web Announcer - Submit your site to 70 search engines in one go.
TrafficZap - Search engine submission
Self Promotion - Information & tools to promote your site.
Who Is - Search for domain names.
Domainit - Easy to use domain registration
Link Alarm - Automatic, scheduled link testing with email notification.
Link Valet - Link Valet is a WWW Link checker. When you enter the URL of an HTML page on the Web, it will fetch the page, and print a report on it. Link Valet will also spider your site.
Meta Tag Analyzer - Check your meta tags for errors and make them more robot friendly.
Spider Food - Search engine tutorials and website promotion.
Add Me - Free search engine submission.
Page Rank - Check your Google page rank.