I will never forget minix. This tiny unix booted from one floppy and ran on the Atari ST (among others). It even had a C compiler. Tanenbaum built it as an OS education tool.
Minix3 has adopted/is adopting parts of the NetBSD codebase (packages, libc, coreutils, etc etc) and is closer to the *BSD platforms than ever before. It can be considered a BSD microkernel nowadays.
There's still a lot to do and packages to port/features to add, but it's getting there. Since the release of Minix3 (I think it was in 2007) the project has gone more towards the pragmatic and practical world, instead of just academia.
Heh, I don't think parent's point is that minix is the most practical small UNIX option now so much as that it was a big deal for them back in their Atari ST days.
As someone who was really trying to get 386BSD when I was kid, I had no idea that minix already ran on my Amiga 500. :( Time machine me would have loved to run this.
