use WWW::Mechanize::Firefox;
  my $mech = WWW::Mechanize::Firefox->new();
  $mech->get('http://google.com');

  my $png = $mech->content_as_png();

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use WWW::Mechanize::Firefox;

my $mech = new WWW::Mechanize::Firefox();

open(INPUT, "<urls.txt") or die $!;

while (<INPUT>) {
        chomp;
        print "$_\n";
        $mech->get($_);
        my $png = $mech->content_as_png();
        my $name = "$_";
        $name =~s/^www\.//;
        $name .= ".png";
        open(OUTPUT, ">$name");
        print OUTPUT $png;
        sleep (5);
}



##</code><code>##

linux-vi17:/home/martin/perl # perl mecha_test_1.pl
   www.google.com
    www.cnn.com
    www.msnbc.com
command timed-out at /usr/lib/perl5/site_perl/5.12.3/MozRepl/Client.pm line 186
linux-vi17:/home/martin/perl # 


##</code><code>##

urls.txt 
www.google.com
www.cnn.com
www.msnbc.com
news.bbc.co.uk
www.bing.com
www.yahoo.com