for me they sowing to many and to big ads on there cpatcha !!
and for this they give bad revene to publishers -.-here is a PHP code example how i implemented captchMe:
require_once("libs/captchme-lib.php");
$privateKey = "84eea1c08cxxx431c680035xxxx61c2";
$authenKey = "31fb92xxx6ff111350405e51xxeda4f02be";
$publicKey = "4891b27e19edexxxxxxcb0ae2e3189b68280xxxxx45bb4ac0";
$response = captchme_verify($privateKey,$_POST["captchme_challenge_field"],$_POST["captchme_response_field"],$ip,$authenKey);
than you cna check with this if captcha was solved:
if( $response->is_valid )
to show the captcha:
$error = null;
$CaptchME = captchme_generate_html($publicKey, $error, $ssl, $customAttributes);
regards