Windows Only, for now - if you program a lot of different Arduinos or other serial port based microcontrollers/TTL-cables/doohickeys, and often have multiple devices connected at once - you may have found yourself hitting up device manager while frantically jerking the USB cable in and out to figure out which COM-port, out of the twelve Arduino Unos that show up, actually belong to the one you just connected.
Well, now there's also this: https://github.com/stg/ComPortNotify
It's a silly problem, most won't even get the point - but for me, it solved a long-standing problem. Well... not really a problem per se - more of an infinitesimal nuisance I suppose. It's kind of like the toothpick in your Victorinox Multitool - who uses that, like ever, right? But it also doesn't get in your way, and may possibly make your day just fractionally better once or twice in a lifetime.
So, here's hoping someone else finds it useful too.
If it saves a few seconds, a few times, in a few more peoples lives than just mine - at some point it just may have saved the world more time then it took writing it.