Package SuperClass.pm
use DBI;
use whatever_else_you_want;
use base 'CGI::Application';

sub cgiapp_init{
   my $self=shift;
   ## initialize variables, stuff them into params to allow
   ## all other modules to inherit common functions. For
   ## instance, I'll set up my DBI connection, user
   ## authentication,  HTML::Template object, etc. all in 
   ## here. Then every object from here on down can access
   ## them.
   }

##</code><code>##

package UserManager;
use base 'SuperClass';

sub setup{
   my $self=shift;
   my $q = $self->query(); #Get CGI.pm object
   $self->start_mode('print');
   $self->mode_param('rm');

   $self->run_modes(
      'login'=>'login',
      'delete'=>'delete',
      'list'=>'list'
      #More run modes here.
   );
}

sub login{
   #do stuff here according to what's inherited from 
   #SuperClass- For instance, use the HTML::Template
   #that SuperClass specifies. This greatly increases
   #reusability.
}