Get Product Collection by Product Type in Magento

$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'));