Not everything in the App Store has to be a Swiss Army knife. Sometimes, you find an app that does one thing and does the heck out of it.
Doughbot is one such app. It tells you where you can buy donuts.
You can also get directions, read Yelp reviews, and look at pictures from Instagram, but that’s just overkill. I can count on one finger the number of bad donuts I’ve had in my life. Just point me toward the nearest besprinkled blip on the map so that I can start pointing at lumps of fried dough I’d like to cram into my face.