For me Christmas Badge Countdown - Christmas Badge Countdown by Michael Hoereth https://appsto.re/gb/bdRiy.i
Bad punctuation, but a sneaky pre-widget way of effectively getting a widget onto the home screen.
And in the post widget world...
SNOWidget - SNOWidget - The Most Magical Widget Ever by Johnny Ixe https://appsto.re/gb/HglO3.i
Gives me a nice countdown in my notification centre. It's showing in the App Store as an iPhone only app, but it works perfectly on the iPad as well.