Killer app? I don't know about killer, but here are some super useful things I can imagine smartwatches doing: 1. Use as a navigation device (walking, driving,

Killer app? I don't know about killer, but here are some super useful things I can imagine smartwatches doing: 1. Use as a navigation device (walking, driving, biking, etc), so you don't have to constantly pull your phone our and check which way to go. 2. Control music / tv / computer from across the room without needing a remote (always on your hand, always paired) 3. Homekit control (lighting, locks, appliances, etc) e.g. set your oven to preheat, go in the backyard and do whatever, watch notifies you when over is ready 4. Healthkit (many people wear health trackers already, this will just bring more features to a device they already wear). Also biometrics. 5. Someone texts / calls / emails you as you sit in a meeting / walking with your hands full / etc you can glance at your wrist and see how important the notification is before you excuse yourself to take the call or whatever. Basically, most of the potential with this device is doing things which phones can already do but in a less intrusive manner. These features alone interest me in smartwatches; I can't imagine what other people will come up with.