Pause/Break key on modern keyboards

In Windows, Windows + Pause/Break opens up the System Properties window. Not exactly relevant to what the key was originally designed for, but still quite useful!

The Pause/Break key can also be used during boot to pause a POST screen so you can read it before continuing. I find it useful when I'm trying to double check that something is detected properly by the BIOS.

Windows supports remapping keys itself: howtoogeek article

Ctrl + Break is still useful on the command prompt to send a break character; but Ctrl + C is a little easier.