It is noted in the code, but I'll repeat it here:

This code is almost entirely copied from the Google Analytics plugin by Terence J. Grant. See his plugin page for details. Credit for the bulk of the work should be his.

Concerning this rendering of the code:

See firestats.cc for information on what Firestats is and how to use it.

Plugin installation consists of:

• Unarchiving the plugin .tgz file to your dokuwiki lib/plugins directory
• Visiting the site Admin ⇒ Configuration page to set the URL for your firestats installation.

An example URL looks like: http://yoursite.com/yourfirestats/js/fs.js.php?site_id=2

dokufirestats/
dokufirestats/action.php
dokufirestats/lang/
dokufirestats/lang/en/
dokufirestats/lang/en/settings.php
dokufirestats/conf/
dokufirestats/conf/metadata.php

<?php 
/*
*
* This code is almost entirely copied from the Google Analytics plugin by:
*
*	Terence J. Grant
*	See: http://www.dokuwiki.org/plugin:googleanalytics
*	
* My changes to the code were made on 05/05/2010.
*
*/

if(!defined('DOKU_INC')) die();
if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN',DOKU_INC.'lib/plugins/');
require_once(DOKU_PLUGIN.'action.php');

class action_plugin_dokufirestats extends DokuWiki_Action_Plugin {

	function getInfo(){

		return array(
			'author' => 'Benjamin Hall (code modified from Terrence J. Grant\'s Google Analytics Plugin)',
			'email'  => 'ben@benhall.com',
			'date'   => '2010-05-05',
			'name'   => 'Firestats Plugin',
			'desc'   => 'Plugin to call firestats on pageload',
			'url'    => 'http://benhall.com/doku/doku.php?id=firestats',
		);
	}
	
	function register(&$controller) {
	    $controller->register_hook('TPL_METAHEADER_OUTPUT', 'BEFORE',  $this, '_addHeaders');
	}

	function _addHeaders (&$event, $param) {
		global $INFO;
		if(!$this->getConf('FIRESTATSURL')) return;
		if($this->getConf('dont_count_admin') && $INFO['isadmin']) return;
		if($this->getConf('dont_count_users') && $_SERVER['REMOTE_USER']) return;
		$event->data["script"][] = array (
		  "type" => "text/javascript",
		  "src" => $this->getConf('FIRESTATSURL'),
		);

	}
}
?>

<?php
$meta['FIRESTATSURL'] = array('string');
$meta['dont_count_admin'] = array('onoff');
$meta['dont_count_users'] = array('onoff');
?>

<?php
$lang['FIRESTATSURL'] = 'Your Firestats Site URL:';
$lang['dont_count_admin'] = 'Don\'t count admin/superuser';
$lang['dont_count_users'] = 'Don\'t count logged in users';
?>