CGI scripts and programs allow WWW pages to be generated dynamically. Here are scripts using the 'safe' extension of perl - ie luserproof - this is somewhat restricting, but still allows some useful things to be done. There are also some C programs. Feel free to copy anything and mangle it to serve your own evil ends.
AmiNet is the world's largest collection of Amiga-related software and is mirrored at several sites around the world. This CGI generates a page containing links to each of the full mirrors. You can specify either a link to an AmiNet directory or to several files within one directory.
You have a choice between a safeperl script or a C version (tar-gzipped)
Random quote generator and search utility, as used on the Oxford Babylon 5 Society's Quotes Page - Look at the source of that page for detailed usage. Simply, given a large database of quotes, split over multiple files, quote returns a quote at random and search returns all those containing the specified phrase.
This script manages the Oxford University Computer Society's World Wide Web Treasure Hunts: managing all aspects from the registering of new teams to keeping track of the current scores.
This is a simple guestbook manager which I wrote for a friend.