Perl
Perl is the defacto language used in CGI programming. It is also a general purpose language that has many other uses beyond the web. If you need a great language to process textual data then Perl is right for for you. This site contains a number of free educational and informational resources on Perl.
CGI (Common Gateway Interface)
CGI is a means of creating dynamic web content. There are times when it comes in handy to generate dynamic web content.
CGI is not confined to a particular language, though Perl is the most popular choice.
If you are planning on getting your site listed with the search engines you will not want to get too crazy with CGI as search engines are designed to gather data from static web pages!
CGI GENERAL INFORMATION
Click on the Wiki globe for the general scoop on CGI
CGI FREQUENTLY ASKED QUESTIONS
The following are links to some site that have compiled nice frequently asked questions lists
http://www.htmlhelp.com/faq/cgifaq.html
http://www.faqs.org/faqs/www/cgi-faq/
RESOURCES / REFERENCE
CGI Security
http://www.w3.org/Security/Faq/wwwsf4.html
Perl
CGI Programming for the WWW book
EDUCATION
CGI
http://users.easystreet.com/ovid/cgi_course/