HTML

Weblint
Like picking lint out of a clothes dryer (where did all that fluff come from?), Weblint will scrutinize your web pages to find any potential problems with the HTML you wrote.

The Bare Bones Guide to HTML
The Bare Bones Guide to HTML lists every official HTML tag in common usage, plus the Netscape extensions.

Netscape's extensions to HTML
This lists all of the new HTML tags recognized by Netscape Navigator (such as tables and colored text). Used well, they will make your Web pages really stand out.

The Netscape Frames Tutorial
Charlton Rose has put together this completely terrific introduction to Netscape 3.0 frames.

How do they do that with HTML?
This site gives several tricks and tips for getting the most mileage out of your web pages.

CGI Programs

The Common Gateway Interface
NCSA provides much helpful information about CGI here (along with a good introduction to forms.)

Server-side includes
Also known as "parsed HTML": what they are, how they work, how to use them.

Using ISINDEX for server-side searches
This explains how to write a CGI script to perform simple text searches on your web server.

Matt's Script Archive
If you just want good scripts without having to write them, try here. Some modifications are usually necessary, which Matt explains in his readme files.