$req .= "&$key=$value";
$header .= "POST /path/to/form.cgi HTTP/1.0\r\n";
$header .= "Host: host.address.com:80\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('host.address.com', 80, $errno, $errstr, 30);
fputs ($fp, $header . $req);