Almost everything you need to create and maintain a web site is available free on the web itself. Here is a list of some useful resources that I came across.

Authoring
JavaScript Reference The Netscape's Javascript documentation
JScript Web Page Microsoft's JScript documentation
The AskAway! Network A unique directory of FAQs
Yahoo! JavaScript Links Yahoo's directory of JavaScript links
Focus on Javascript About.com's Javascript directory
The Web Design Resource Everything related to web site design
Doc Javascript Javascript tips and lots of how-to columns
The JavaScript Source An excellent "Cut & Paste" JavaScript library
Website Abstraction Tutorials, scripts, applets, discussion forum...
Dynamic Drive Free DHTML scripts to add to your site
JavaFile A good collection of free Javascripts
JavaScript-Intro by Voodoo A very through Javascript tutorial.
JavaScript School A good Javascript language tutorial.
The JavaScript Planet Lots of free Javascripts
NCSA-A Beginners Guide to HTML The best site to start

Webmaster Tools
WebPosition Monitor and improve your site's ranking
GifCruncher Reduce the size of your GIF images
ListBot Add a free mailing list to your site
Extreme Tracking Track visitors to your web site
VantageNet Web Services Free discussion forum and polls
WebmasterBoard Discussion Forum for Webmasters

Ad Networks
If you run a small to medium website and are looking for ways to generate a revenue, check out these sites:

Burst! Highly recommended. Offers both per-impression and per-click banners.
BClick Offers both per-impression and per-click banners. Recommended.
WebSponsors.com Link to free or trial offers and get paid. Recommended.
The Advertising.com AdNetwork Offers both per-impression and per-click banners.