This is a real world application which can be used in every single day for your personal use. It's a simple yet tricky website blocking program built on python runs on the background and what it does is, it doesn't let you browse certain distracting websites such as Facebook or Twitter or your mail account during your working hours.
The idea is that once you build this program you pass to the program website links as strings that you think are distracting. You may also pass the time that you are working on your computer and the program will block these websites during these working hours. And in that way you not only are much more productive but this also reduces stress as distraction is also known to cause stress.
This program is tested to work on Windows, Mac and Linux.