Drupal diskuze:
http://drupal.stackexchange.com/questions/1027/how-to-do-a-date-countdow...

Drupal moduly:
https://www.drupal.org/project/jquery_countdown_timer
https://www.drupal.org/project/field_timer
https://www.drupal.org/project/field_countdown
https://www.drupal.org/project/jstimer
http://druu.org/drupal-modules/count-down

Jiné:
https://www.tickcounter.com/