Creating a Free Shipping Category in Magento. Step 1: create a basic Catalog Category in the Magento admin. Take note of the category_id. Step 2: Copy the Core file app/code/Core/Mage/Catalog/Block/Product/List.php to your local directory app/code/local/Mage/Catalog/Block/Product/List.php Step 3: Modify the _getProductCollection() function like …

List.php

<?php
/*
Rest of the file above this
app/code/local/Mage/Catalog/Block/Product/List.php
*/

   protected function _getProductCollection()
    {

        if (is_null($this->_productCollection)) {

            $layer = $this->getLayer();
            /* @var $layer Mage_Catalog_Model_Layer */
            if ($this->getShowRootCategory()) {
                $this->setCategoryId(Mage::app()->getStore()->getRootCategoryId());
            }

            // if this is a product view page
            if (Mage::registry('product')) {
                // get collection of categories this product is associated with
                $categories = Mage::registry('product')->getCategoryCollection()
                    ->setPage(1, 1)
                    ->load();
                // if the product is associated with any category
                if ($categories->count()) {
                    // show products from this category
                    $this->setCategoryId(current($categories->getIterator()));
                }
            }

            $origCategory = null;
            if ($this->getCategoryId()) {
                $category = Mage::getModel('catalog/category')->load($this->getCategoryId());
                if ($category->getId()) {
                    $origCategory = $layer->getCurrentCategory();
                    $layer->setCurrentCategory($category);
                }
            }
            


            /* My Addition */

            $cat_data = $layer->getCurrentCategory()->getData();
            $cat_id = $cat_data['entity_id'];

            if ($cat_id == 471) { // WHAT IS THE CATEGORY ID YOU WNAT TO SHOW ONLY FREE SHIPPING PRODUCTS
            	
                $collection = Mage::getResourceModel('catalog/product_collection')
                    ->addAttributeToFilter('free_shipping_discount', array('eq' => '1083')) // I named my attribute free_shipping_discount. Value 1083 = 'Yes'. Trick you can see Attribute ID values in the Magento Admin.
                    ->addAttributeToSelect('*');

                $collection->load();

                Mage::getModel('catalog/layer')->prepareProductCollection($collection);

                $layer->setProductCollection($collection);
                $this->_productCollection = $collection;


            } else {

                // stock Magento

                $this->_productCollection = $layer->getProductCollection();

            }

            /* End My Addition */


            $this->prepareSortableFieldsByCategory($layer->getCurrentCategory());

            if ($origCategory) {
                $layer->setCurrentCategory($origCategory);
            }
        }

        return $this->_productCollection;
    }


/*
Rest of the file below this
app/code/local/Mage/Catalog/Block/Product/List.php
*/

?>

<?php
$category = Mage::getModel('catalog/category')->load(471); // your category

$visibility = array(Mage_Catalog_Model_Product_Visibility::VISIBILITY_BOTH, Mage_Catalog_Model_Product_Visibility::VISIBILITY_IN_CATALOG);

$collection = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('free_shipping_discount', array('eq' => '1083'))
->addCategoryFilter($category)
->addAttributeToFilter('visibility', $visibility)
->addAttributeToSelect('*');

$collection->load();

Mage::getModel('catalog/layer')->prepareProductCollection($collection);
?>

<?php
//best sellers by category

$category = Mage::getModel('catalog/category')->load(471); // shop category

$visibility = array(Mage_Catalog_Model_Product_Visibility::VISIBILITY_BOTH, Mage_Catalog_Model_Product_Visibility::VISIBILITY_IN_CATALOG);

$current_page = Mage::getBlockSingleton('page/html_pager')->getCurrentPage();

$collection = Mage::getResourceModel('catalog/product_collection')
    ->addAttributeToSelect('*')
    ->addCategoryFilter($category)
    ->addAttributeToFilter('visibility', $visibility); 

$collection->getSelect()
    ->joinLeft(
        'sales_flat_order_item AS order_item',
        'e.entity_id = order_item.product_id',
        'SUM(order_item.qty_ordered) AS ordered_qty')
    ->group('e.entity_id')
    ->order('ordered_qty DESC')
    ->limit(25);

$collection->load();

Mage::getModel('catalog/layer')->prepareProductCollection($collection);

$this->_productCollection = $collection;

?>