The Scheduled Actions module allows you to tell Drupal to perform some action (publish a node, send an email) at a later time. With it, you can obey that ancient dictum, "Never do today what can be put off until tomorrow."
To use Scheduled Actions, you must first install the Actions module and the Scheduled Actions module. Enable both modules, then visit administer >> actions to initialize the Actions module. Go to administer >> access control and grant the schedule actions permission to the appropriate roles. Finally, you must have cron enabled for your site.