PHP Example
Screen shot
index.php

<?php
$filename=\"counter\\data.txt\";

if(file_exists($filename))
{
$handle = fopen($filename, \"r\");
$counter = (int)fread($handle, 20);
fclose($handle);

$counter++;

echo \"Your Vistor Number \".$counter;

$fp=fopen($filename,\"w\");
fwrite($fp,$counter);
fclose($fp);
}
?>

You can download source code here