E M 167, my (educated, but possibly mistaken) impression was that anything with a microprocessor in it (microwave ovens, TV monitors, and computer monitors all contain microprocessors) is unlikely to use the 60Hz line frequency for timekeeping. Pretty much all microprocessors require a crystal oscillator (well, many of them contain on-chip all of the oscillator circuitry except the quartz crystal itself), running at a fairly high frequency. This is (more or less) the frequency you see reported as the "speed" of a PC, and is typically anywhere from 1MHz in small or old microprocessors up to several GHz in the latest PC CPUs. I believe it's easier (for safety and certification reasons) to scale this high frequency down to something useful for timekeeping than it is to get the 60Hz signal from the powerline down to a safe voltage for use inside the chip.

The only clocks likely to use the 60Hz powerline as a timekeeping standard are older electromechanical models, which use a synchronous motor driving a gear train to move the hands.

Anyone else remember the old electromechanical _digital_ clocks? They had flaps with numbers painted on them, often split across the middle, so the top and bottom halves could be slid out of the way separately, driven by gears from a synchronous motor.