Re: Absolutely amazing...
And some more here:
1) a couple of network monitors, showing connectivity and status of various items on my network (which to be fair is displayed via either a Pimoroni Blinkt or a Unicorn pHat, so is indeed turning LEDs on and off).
2) At least 3 media players around the house, plus my travelling one which is currently in storage.
3) My VPN server for when we're allowed to go travelling again.
4) My internet radio that's providing the background music whilst I type this.
5) My PiHole network ad blocker
6) My general purpose server, running Calibre, Plex, Node Red plus file serving.
7) My magic mirror/desktop info display.
8) The "play" box that my kids use for Minecraft, Python, Scratch, web browsing and all sorts of other stuff.
So slightly more than lighting an LED or two from the GPIO pins.