Drinktrack
I wrote Drinktrack to track my intake of alcohol, which was much greater back then. Drinktrack featured a really quick “drink entry” (perfect for when out and about), Dark Mode before it was cool (for dark clubs) and pretty graphs to tell you how much you should regret the night before.
It was sold at $0.99 and managed to sell a few copies a month. I stopped updating it for new iOS versions in 2015.
The original website: Drinktrack - iPhone app to track units and calories