I never use Caps Lock, so I disable the Caps Lock key completely with xmodmap, to avoid hitting it by accident.

Occasionally my X server gets into caps-lock state anyway. (Usually some complicated stunt was involved, like attaching x11vnc to the display remotely.) And then I can't turn it off again using the Caps Lock key.

So I wrote a tiny X client that lets me type 'xcapslock off' at a shell prompt …

… and then I had to make an alias to it, called 'XCAPSLOCK OFF'.