Получить коллекцию товаров по типу:
$collectionSimple = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('type_id', array('eq' => 'simple'));
$collectionConfigurable = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('type_id', array('eq' => 'configurable'));
$collectionBundle = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('type_id', array('eq' => 'bundle'));
$collectionGrouped = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('type_id', array('eq' => 'grouped'));
$collectionVirtual = Mage::getResourceModel('catalog/product_collection')
->addAttributeToFilter('type_id', array('eq' => 'virtual'));