A couple of years ago I was given an old radio from my mom. I wanted it because it looked cool and thought that it would look nice on a shelf. Turned out that it still worked, or more accurately, still turned on. I was able to do some simple wiring and cram in an airport express and when I was done I had a wireless speaker.
Since then I’ve made a half dozen more, each time tweaking the schematic to either match the radio or give it some new features. It’s become a bit of a passion project for me. My current project is to create one that is rechargeable and Bluetooth.