Perimeter is a system that uses gps tracking and user preferences with geofencing on a smart phone to control any arbitrary hardware devices.
For example, imagine driving home from work and when you get within a 10km radius of your house, your thermostat is automatically turned on. Then, when you're 30m from home, your lights turn on and the app pushes a notification prompting for a password to unlock your door. After entering it, you go inside to a warm, lit home, with a fresh smoothie.
The possibilities are endless. The system is very broad, and it can be customized with any number of different hardware outputs and controlling preferences. The back end is supported by a custom built server, which bridges your phone (via an api) and your hardware (via serial or wifi).