For those who don't know who Alan Cox is, he was the Linux 2.2 branch maintainer, is still heavily involved in Linux, and also does lots of other neat shit.
I used to have a 1.44Mb floppy that booted QNX to a desktop environment. Of course, that's not so unusual historically: both Amiga and GEM had single-floppy desktop enviroments (or did the Amiga require two to get to Workbench?)
(That's actually quite big for a tiny-computer OS, although it's the smallest Unix I know of.)