Sound sensing, navigation, and obstacle detector.
Usefull project when you wake up at night for washroom the PIR Sensor Senses your Motion and turns the tube light on.
A generic setup for museum exhibit automation. DFRobot 4 relay shield 2.1 and screw shields, Hitachi 16*2 Display shield on UNO or Mega.
Example of diy smart socket. This can be controlled by ESP8266 Home application. With this smart socket you can on/off any device in home.
Home Automation: control various home appliances with the help of voice recognition.