Badge Countdown is probably the best Countdown App in the whole AppStore.
Badge Countdown: See how many days are remaining to your event even when the app is closed
Import from calendar: Import events stored in your iPhones calendar
Notifications: The app notifies you e.g. when a countdown ends
Swipe between formats: Really cool feature, just slide up
and down between different time formats e.g. just seconds
So what are you waiting for??
Check this app out!