My college had an (experimental?) machine they got from Acorn that dual-booted into a 'nix OS. It got stuck in a corner and forgotten about, but if it had been a few years later I think it could have been an amazing project for them.
When I was in secondary school, we had a plain grey, all-in-one keyboard and system desktop case that had a microdrive and was connected to a hacked colour TV via a massive umbilical cord. It turned out to be a BBC Micro prototype.