You may have seen Hans Sander's "Piano Tuning Alarm Clock" device at PTG events. This is a clever service reminder to give your favorite clients who are on a once-a-year service schedule.
This 1.5" pre-programmed 365-day timer has a single reset button, and displays the countdown throughout the year. When it reaches zero, it will flash and beep every 5 minutes to let the client know it's time to have the piano tuned. Pressing the rest button will turn off the alarm and reset it to a new 365-day countdown. The adhesive foam tape backing allows it to be stuck to refrigerators, etc.