My gas stove with an electric oven. It works, but barely.

I have an old CD Walkman that still works just fine. Although looking at the logo alone, it's most likely made after the year 2000, so it's not that old.

Mine’s the 390t with 256mb of storage. So it’s one of the ones that’s triangle in shape with a real smal lcd screen and takes a single AA battery. Suuuuper simple to just plug in with mini USB and drag and drop mp3s over.

Probably my Canon 5D Mark II DSLR that I bought at launch (2008). Still works fine hundred of thousands of clicks later, multiple trips across the world, etc etc. It even still holds a candle to my current camera on the photo side of things (video specs definitely dated now though).

I have a spring/crank music box stuffed animal from when I was born (several decades) that still sounds perfect.

GameBoy Color with a single game: Pokémon Red.

Next time I was able go to the shop they had upgraded to GameBoy Advance and no GB/GBC games were to be never found again. It was the best/worst thing I ever got. :'(