I was recently watching a YouTube video from the excellent channel Le labo de Michel, where he reverse-engineers a WL201EED2 RPM indicator for a jet engine. This particular indicator has a lovely imitation of a mechanical counter using tiny green LEDs. Especially compelling is the way in which the digits "roll over," an artifact of how mechanical counters are implemented using a line of disks, those for less significant digits pushing on those for more significant digits once per revolution.

Lots of equipment from aviation seems to use skeuomorphic design principles like this one. I'm not sure if pilots actually find mechanical counters which "roll over" easier to read than those whose digits flip instantly, but the aesthetic quality of the rolling over is compelling to me (and, apparently, to lots of others going by the comment section of the video).

To pay tribute to this neat design, I reproduced the animation using some SVGs and a little JavaScript. You can click anywhere on the dial to move the pointer to a different location.

The original indicator has a red lamp which alerts the operator when the RPM is too high, but I haven't implemented that particular feature. Perhaps later.