Good for showing labels/descriptions that accompany custom fields when they are set, and avoiding lots of empty labels.
Eg: if there is no content set in the 'project-agency' field, don't show the label 'Agency:', but if there is, show it with the content.

<?php
$themeta = get_post_meta($post->ID, 'project-agency', TRUE);
if(!empty($themeta)):
?>
 
<strong>Agency:</strong> <?php echo get_post_meta($post->ID, 'project-agency', true); ?>
 
<?
endif;
?>