Shopping lists were always a pain for me. One item is at one store, and another item is at another store. The answer to this is maintain separate lists. However, sometimes a given item can be found at either store, and crossing it off one list has it remain on the other.
The first iOS (then iPhone OS) app I ever made was the solution to this problem. The app has a single list of items and allows items to be added to multiple specified stores. Then, each store’s list is automatically generated and checking each item off marks it as purchased everywhere. The item can even be automatically added back to the list after a specified period of days.