Remote Camera Shutter (Google Camera)
Similar to LookBehind mentioned above, those with the official Google Camera app (or select smartphones) can use a smartwatch as a remote to take photos or record a video.
Using Google Camera you can launch the app from Android Wear, and tap to snap a photo using a smartphone setup elsewhere, or on a tripod. This is perfect for group photos, sneaky photos, and an array of other things. There's multiple similar apps in the Play Store, but using the built-in feature and Google Camera is your best bet.