Mason - a powerful Perl-based web site development and delivery engine. With Mason you can embed Perl code in your HTML and construct pages from shared, reusable components. - http://www.masonhq.com/
Axkit - XML web publishing with Apache and mod_perl. - http://axkit.org
Embperl - a system for building dynamic Websites. It gives you the power to embed Perl code in your HTML documents and the ability to build your Web site out of small reusable objects in a OO-style. - http://perl.apache.org/embperl/
Template Toolkit - A fast, powerful, extensible template processing system well suited to the production and maintenance of web content and dynamic document systems. - http://www.template-toolkit.org
HTML Template - Templating module for Perl with added features for Apache/mod_perl. Module is distinguished from others serving a similar purpose by a clear distinction between programming and layout. - http://sourceforge.net/projects/html-template/
Apache::ASP - a perl-based version of Active Server Pages. - http://www.apache-asp.org/
OpenInteract - a web application environment for mod_perl - http://www.openinteract.org