util-linux is one of those great "behind the scenes" projects that keeps Linux working. kzak has maintained it tirelessly while at the same time avoiding doing anything stupid (eg. rewriting it all in language-du-jour).
There are also the GNU coreutils which, uh, basically seem to support every single processor and OS capable of running any kind of *nix-ish thing. I believe I even saw mentions of Siemens UNIX (SINIX)!
> used by all mainstream Linux distros (as well as by Systemd haters ;-)
yak yak yak...
Edit: Note btw that this is actually about it being 10 years since he forked util-linux to util-linux-ng because he considered the former as having been abandoned (or developing too slowly).
Also don't forget the spin-offs, like the mini-library for formatting tables of data (http://git.kernel.org/cgit/utils/util-linux/util-linux.git/t...).