You can remove or change the "meta generator Joomla! - Open Source Content Management"
Although (as you can probably tell), we have a love affair with the Joomla CMS, for various reasons, some times you don't want to show that your website is driven by Joomla. Something which will give away your content management system is the meta generator tag. Fortunately, it is very easy to remove this.
?php $this->setGenerator('My Company Ltd or any generator which you prefer'); ?>
This simple line will change the generator tag to anything which you put in between the quotes.
The following is how it will look on the default rhuk_milkayway template:
...<jdoc:include type="head" />
<?php $this->setGenerator('My Company Ltd or any generator which you prefe'); ?>
<link rel="stylesheet" href="<?php echo $this->baseurl ?>/templates/system/css/system.css" type="text/css" />...
You can also choose to add this in your index.php for Joomla 2.5 templates
Another trick to customize your Joomla website :)