In case you need to export to a csv all the categories in your site, here is the code.
The csv just has the ID of the category, the Name of the category and the url key
$categories = Mage::getModel("catalog/category")->getCollection()
->addAttributeToSelect('name')
->addAttributeToSelect('url_key');
fputcsv($file,array('Category ID', 'Name', 'URL Key'));
// id, name, url-key
foreach($categories as $_category)
{
fputcsv($file,array($_category->getData('entity_id'), $_category->getData('name'), $_category->getData('url_key')));
}
fclose($file);