Perl: The Perl home page is at http://www.perl.com/ and includes links to distributions, tutorials, documentation, frequently asked questions and more. This is a good launching pad for information about Perl and for keeping up to date on the latest versions of Perl and its modules.
DBI: The Perl “Database Interface”, a set of modules to provide a generic API (DBI) and drivers to specific databases (DBD), allows for portable access to a large number of databases. Information about DBI is available from the Perl home page, as well as from http://www.hermetica.com/technologia/perl/DBI.
Apache: The Apache web server, used on a majority of web sites, is freely available from http://www.apache.org/ in source format. Documentation for Apache, as well as tutorials on how to use and administer it, can be found at that web site or http://www.apacheweek.com/, a weekly newsletter for Apache users.
MySQL: The MySQL home page is at http://www.mysql.com/, although there are numerous mirrors around the world. Some additional MySQL documentation can be found at http://www.turbolift.com/.
Database-Backed Web Sites, a book by Phil Greenspun on the creation and maintenance of databases and web sites, is a classic that should be read by anyone using these tools. See http://photo.net/wtr/ for a full copy of the book (as well as a draft of the coming sequel), along with many other useful tidbits. While I did not use his code when designing this system, I did use some of his ideas about formatting and presentation. So while the systems don't share any code, they do have a similar “look and feel”.
All listings referred to in this article are available by anonymous download in the file ftp://ftp.ssc.com/pub/lj/listings/issue58/3252.tgz.