WordPress Spam Comment HoneyPot

comment-honeypot.php

<?php
/*
Plugin Name: Comment HoneyPot
Description: Disallows any comments from users who add a url to the invisible webpage form field
Author: Tim Whitlock - Mods by Ed Cooper
Author URI: http://timwhitlock.info/
Version: 0.1
*/

function _tw_intercept_comment( array $data ){
  if( empty($data['comment_author_url']) ){
    return $data;
  } else {
    $message = 'Sorry, we capture spammers who add a web address to the comment form as it\'s hidden. Try writing your comment again without including a web address this time.<br/><br/>If this is an error please let us know at <a href="http://yoursupportsite.com" target="_blank">Your Support Website</a><br/><br/><a onclick="history.go(-1)" style="cursor:pointer;"><strong>Go Back</strong></a>
    $title = 'Spam Block';
    $args = array('response' => 200);
    wp_die( $message, $title, $args );
    exit(0);
  }
} 

add_filter('preprocess_comment','_tw_intercept_comment'); 

?>