This video will show you how to make an IoT button which is similar to that of Amazon Dash button. Instead of Button You can even attach a sensor and you can program to do the tasks like,
Whenever anyone enters my room, it will send user a message. Requirement – Door sensor+IoT Button
Whenever the user enter the room, turn on the AC. Requirement -GPS of smart phone + IoT Button+IR transmitter
You can also use it as a wireless whether broadcaster, It will notify you whenever their is rain outside your home and even to notify you whenever temperature goes beyond the threshold level. Requirement -water sensor,Temperature Sensor, IoT button
Their are lot other applications of this little button.Make a one for you and lets us know for what application you made one.