[zvr]

Too many to count, over decades. Ranging from small scripts to full-fledged applications. Some get used weekly (if not daily) after years, some much less so, since conditions and environments change.

The one that had the most impact on my physical life: many years ago when I had RSI, even clicking the mouse button was a pain. I wrote a utility that looked at mouse movements, and when the mouse stopped and remained still for a second or two, automatically "clicked the mouse button". So I only had to move the mouse and wait a little, and clicking became automatic. It was pretty straightforward to implement on X11, my environment at the time. Later I wanted to have the functionality on Windows but never found anyone who knew programming that platform that well (I don't even know whether it's possible).