As many folks of Finnish descent are want, we have a sauna. Each night someone is tasked with monitoring the temperature. What better application for a RaspberryPi to announce via social media, that the desired temperature is reached?
Here is an offering via GroupMe:
It’s pretty basic, but a temperature sensor is connected to a RaspberryPi which has a wireless connection to the internet. With a little work, it’s integrated (securely) into a popular social media platform.