Just switch on the Baby Monitor app and it will alert you if your baby starts crying. Based on your preference, it will call you or SMS you, play a lullaby or even playback a message you have recorded for the baby.
The World Chess Championship 2014 app, helped all chess enthusiasts to follow World Championship match - Magnus Carlsen - Vishwanathan Anand live and made following games social with additional features such as live chat, news, interesting facts, move by move analysis etc. The app also had amazing functionalities such as discussion with your social media friends in Facebook, Google +, Twitter etc.
Measure the ambient temperature with inbuilt temperature sensor. The app allows you to track temperature at various intervals and plot how the temperature has varied over a period time