function alexa() {
    $domain = "http://data.alexa.com";
    $keylength = 14;      // the resulting length of the keyid.  14 and 15 were seen in the wild.
   
    // session_start() must have already been set.  If so, this will ensure that each visitor maintains the same keyid throughout the entire visit.
    if (isset($_SESSION['alexa_keyid'])) {
  $keyid = $_SESSION['alexa_keyid'];
    } else {
  $keyid = substr(str_shuffle("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"),0,$keylength);
			$_SESSION['alexa_keyid'] = $keyid;
    }
   
    $cli = "10";     // ???
    $dat = "snba";   // ???
    $ver = "7.2";    // version number of toolbar?
    $cdt = "alx_vw"; // ???
    $wid = rand(0,32767);  // appears to be a random integer initiated when the browser starts.
    $act = "00000000000";  // ???
    $ssarray   = array ("800x800", "1024x768", "1280x768", "1280x800", "1280x1024", "1600x1200", "1680x1050", "1920x1200");
	
    shuffle($ssarray);
    $ss  = $ssarray[0];    // browser screensize.  Resulting value is chosen at random from an array of values.
    $bw  = "1523";   // bandwidth? probably used in calculating metrics related to visitor connection speeds  (noted values are close to common
         // connection speeds like 768k, 1mb, 1.5mb, etc.)
    $t   = "0";      // ???
    $ttl = rand(200,1000); // time-to-live?  probably used in calculating average load times
    $vis = "1";      // ???
    $rq  = rand(15,80);    // appears to increment with each toolbar request
    $url = “http://<<<PUT YOUR DOMAIN HERE>>>/”;
 
    $params="/data/".$keyid."?cli=".$cli."&dat=".$dat."&ver=".$ver."&cdt=".$cdt."&wid=".$wid."&act=".$act."&ss=".$ss."&bw=".$bw."&t=".$t."&ttl=".$ttl."&vis=".$vis."&rq=".$rq."&url=".$url;
   
    return $domain.$params;   
}

// êîä íèæå íóæíî âñòàâèòü êóäà-òî â âàø ñàéò, ÷òîáû ðàíê íàêðó÷èâàëñÿ

<? echo "<img src='".alexa()."' height='0? width='0?>"; ?>