From wayne a. lee:
RestTimerX is a utility for Mac OS X that reminds you to take breaks from typing, at intervals you specify. It operates in a similar way to Kensington MouseWork's "Rest Reminder" featureÃ¢??however, since the current beta version of MouseWorks for Mac OS X is missing "Rest Reminder", I decided to write my own replacement.
RestTimerX now uses a big, translucent red banner (always on top, can't be hidden) to remind you to take a break, rather than the regular alert box of v1.0d1 . It does not actually prevent you from working, though, so you can still save that document you were working on; and since it's translucent, you can still read onscreen documents while resting. But it's a pretty annoying banner! Hopefully it's annoying enough for you to actually stop working!
The banner also features an onscreen timer which lets you know how much rest time is left. If you continue to work during your rest time, the banner remains, and the "rest time remaining" timer will reset to its maximum value! Once the rest time has elapsed, the banner will disappear.