Include Magento blocks outside Magento

gistfile1.php

/*
 * Initialize magento.
 */
require_once 'app/Mage.php';
Mage::init();

/*
 * Add specific layout handles to our layout and then load them.
 */
$layout = Mage::app()->getLayout();
$layout->getUpdate()
    ->addHandle('default')
    ->addHandle('some_other_handle')
    ->load();

/*
 * Generate blocks, but XML from previously loaded layout handles must be
 * loaded first.
 */
$layout->generateXml()
       ->generateBlocks();

/* 
 * Now we can simply get any block in the usual way.
 */
$cart = $layout->getBlock('cart_sidebar')->toHtml();
echo $cart;

Taken from: http://stackoverflow.com/a/6357605/486872