Henry Minsky, Marvin's son, works at Nest on the "Thermogotchi", a digital pet that lives on your wall, that's a sensor-driven, Wi-Fi-enabled, self-learning, programmable thermostat which you train to adapt to your habits and lifestyle, and keep happy by feeding love and energy.
http://www.beartronics.com/
Google liked the idea so much that they acquired the company that developed it. So if that isn't a practical application of AI, I don't know what is.