The Woolworths app for Android and iPhone is an example of a supermarket app done right. Aside from the fact that it's available on more than one platform, it has a bunch of actually useful features. It allows you to set a preferred store, then lays out your shopping list according to that store's floor plan; you can scan barcodes at home to add items to your shopping list; helps you find products; and even offers you daily specials and deals. It genuinely streamlines the shopping experience.
For Android, iPhone