App idea for someone: make a simple alarm.<p>I have a few Nest devices, and they all do motion detection. If I'm away for a few days, I'd love an alert if my Nests detect someone in the house. It could alert me to check a security camera, and then to call the police.<p>It could do fancy stuff, like only alert me if I'm not at home by checking my phone's location. Or perhaps you could set off the fire alarm to try and ward off intruders.<p>I imagine alarm systems are on Nest's roadmap. I'd be worried if I was ADT.