Add related products to order success page Magento::

Suppose you want to show the related products of the products that ordered. In the order success page you will see those related products. lets do this & enjoy :

>> Create a block in checkout.xml
    <reference name="right">
            <block type="catalog/product_list_relatedsuccess" name="catalog.product.relatedsuccess" before="-" template="catalog/product/list/related.phtml"/>
        </reference>
>> Then create the Relatedsuccess.php page copy from Related.php under app/code/core/Mage/Catalog/Block/Product/List

>> Change the class name Mage_Catalog_Block_Product_List_Related to Mage_Catalog_Block_Product_List_Relatedsuccess

>> Then find this method _prepareData()  and replace with following...
    protected function _prepareData()
        {
            $order_id = Mage::getSingleton('checkout/session')->getLastRealOrderId();
        $order = Mage::getModel('sales/order');
        $order->loadByIncrementId($order_id);
        $items = $order->getAllItems();
        $relIds = array();
        foreach($items as $_item){
            $relprodColl = Mage::getModel("catalog/product")->load($_item->getProductId())->getRelatedProductCollection();
            foreach($relprodColl as $prod){
                array_push($relIds, $prod->getId());
            }
        }
        $this->_itemCollection = Mage::getSingleton('catalog/product')->getCollection()->addAttributeToFilter('entity_id', array('in' => array_unique($relIds)));

            return $this;
       }

>> And load the product in the related.phtml page to get all contents.