This hack comes becomes very useful when you are running a contest because you might be posting information such as clues or hints that you don’t want to stay up for ever. Instead of manually removing the article, you can just make it expire automatically. It also works if you have a product that you are offering a discount on. You posted it on your blog, but you don’t want that discount to stay on your blog after its over. So you can remove it automatically with this code. Your loop would need to look like this:

<?php
if (have_posts()) :
while (have_posts()) : the_post(); ?>
$expirationtime = get_post_custom_values('expiration');
if (is_array($expirationtime)) {
$expirestring = implode($expirationtime);
}

$secondsbetween = strtotime($expirestring)-time();
if ( $secondsbetween > 0 ) {
// For example…
the_title();
the_excerpt();
}
endwhile;
endif;
?>

  Note: You may have to customize the codes to fit the look of your theme. Once you pasted this code, you can use custom fields when writing a post to set an expiration date. Make sure you select the key “expiration” and use the the following date format: mm/dd/yyyy 00:00:00