Ask HN: What are good smartwatch app use cases?

I'm curious what smart ideas you all think we'll see from the coming wave of smartwatch apps.

For example, Dominos released their pizza ordering smartwatch app http://www.eater.com/2015/3/2/8135967/dominos-new-smartwatch-ordering-app

What other things make sense? I'm really just hoping to spark a discussion on this.