Saent - A device to reduce distraction, like a fancy pomodoro timer.
Time Out - Break timer with micro-breaks for Mac OS X.
Focus App - New Tab page that gives you a moment of calm and inspires you to be more productive.
Breaktime - Break time is an app that reminds you to stand up every chosen amount of time.
Escape - Track all your unnecessary trips to distracting websites
restbreak - This free program reminds you to take regular computer rest breaks.