How to add new Attribute options programmatically in Magento

Example:

$arg_attribute = 'manufacturer';
$arg_value = 'value to be added';

$attr_model = Mage::getModel('catalog/resource_eav_attribute');
$attr = $attr_model->loadByCode('catalog_product', $arg_attribute);
$attr_id = $attr->getAttributeId();

$option['attribute_id'] = $attr_id;
$option['value']['any_option_name'][0] = $arg_value;

$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$setup->addAttributeOption($option);

Note: This example taken from the webspeaks blog.

For more detail click here webspeaks