# FILE: main script
use strict;
use warnings;
(my $module) = $ENV{PATH_INFO} =~ m!^/([^/]+)/;
# mind this regex, I'm coming back at it in a few secs!

require "$module.pl";
my $content = $module->run();

#...
print $header, $content, $footer;


# FILE: any random module, let's say myawesomemodule.pl
package myawesomemodule;
use strict;
use warnings;

sub run {
    ...
    # generate content
    return $content;
}

1; # hey; it's a require after all.