Accessing files, pages 518-533 of the text.
Mailmerge, pages 437-439 of the text. Allows form data to be saved to a file, or sent via e-mail. You define what the input form looks like, and what the output looks like. Mailmerge is only for writing files, not reading them.
SWISH and wwwwais, pages 439-453. This is the script that allow users to search for keywords on your site. The book explains how to download it and install it. Note that words inside HTML tags are not indexed. This includes heading tags and title tags, too.
Push, pages 566-569 of the text. The clock example from the book, and an example that changes the background color and text color every second.
Pull, pages 565-566 of the text. A simple example that does a countdown.
File Upload, pages 553-556 of the text.
Cookies, pages 536-541 of the text. A few scripts that show how cookies can be set and retrieved
CGIWrap, not covered in the book. Here are two links to the same script. The script tries to access a file that has rw access only for downeyt. The first script will fail to open the data file. The second will be able to open the data file and append data to it.