The idea behind Time Out is that 15 minutes of computer-free time is the perfect way to reset the mind and get a "time out" from thinking without diving head first into distracting activities like checking Facebook or playing video games. Designed by a teacher to keep kids off the computer for long stretches, it also works to remind the adult user it's time for a stretch.
The app comes as a script that you can run at any time by double-clicking the unzipped file. It comes with the Windows version, as well, so you can install this on as many machines as you want. After installation, start the script by clicking it and it will automatically start a time out. There are ways to automate the process, as well, setting up a timeout every X number of minutes or hours so that you stop working, stand up, stretch, and get your eyes off the screen; it's great for anyone who spends long hours at a desk.
Time Out is a useful app for a number of situations: whether you spend a lot of time on the computer every day, teach children who are frequently distracted by the apps on a computer, or want to ensure you're getting up every 45 minutes to stretch your legs.