This sounds like fun – I have a Raspberry Pi sitting on my desk at home doing all of nothing:

Do you like Unix? Do you really like Unix? Well, what if I told you there’s a little-known operating system out there that’s more Unix than even Unix is. Cool, right?

Well it is true! Plan 9 occupies an interesting niche in the open source operating system world. It is a full-fledged descendant of Unix, but not in the way that most systems out there are. It took the bones and beating heart of Unix and then built a brand-new cybernetic exoskeleton around it, with lasers, and heat vision… oh wait. You want to boot this bad-boy up, right? Well, okay, we’ll do that. But what hardware shall we run it on? Hey, you got a Raspberry Pi? Well then, read on!

I’m not sure why it sounds more reasonable to install Plan 9 on a tiny cheap computer than to put it on a full size computer where one could actually have some elbow room for one’s experimentation, but there’s something indisputably cool about the thought.