Time Out - Break timer with micro-breaks for Mac OS X.
Workrave - Workrave is a program that assists in the recovery and prevention of Repetitive Strain Injury (RSI).
stretchly - break time reminder app
Eye Break - eyeBreak is a tiny app designed to sit in the Windows tray and provide a non-ignorable message...
StretchMinder - Work break timer with guided movement & breathing exercises
AntiRSI - AntiRSI is software designed for Mac OS users that helps them in preventing stress, which can cause them different health issues.