μTemplate is the simplest possible template renderer I could write in PHP.

Usage:

/* template.php */
<?php
<h1><?=$title?></h1>
<p><?=$content?></p>
?>
---
/* myapp.php */
include('class.utemplate.php');
$context = array(
    "title" => "Hello, World!",
    "content" => "How's the weather?",
)

uTemplate::render($template_path, $context);