That old Android phone gathering dust in your drawer is a fully equipped sensor platform. It has a camera, microphone, ambient light sensor, barometer, accelerometer, proximity sensor, and a touchscreen - all connected to your WiFi network. Instead of recycling it or letting it rot, you can turn it into a motion-detecting security camera, a room environment sensor publishing data over MQTT, or a wall-mounted Home Assistant dashboard that rivals commercial smart displays costing $150 or more. The entire setup runs on free or near-free software, keeps your data local, and takes about an hour to configure.