NodeOS 1.0-RC1
The best advantages of such a system are performance and memory foot-print, since there are no intermediate layers between the Node.js binary and the Linux kernel making Node.js applications to run almost on the metal, but also making it easier to understand and learn since all the applications are written in Javascript and it's code is easily accesible. It has some particular characteristics that make it different of other OSes, like a build system fully managed by the npm package manager, full unpriviledged access to system devices in a secure way, or the combination of OverlayFS and chroot jails to provide per-user root filesystems, allowing to each of them to create its "own" OS inside NodeOS while being isolated from the other users.
The project was winner on the systems category of the spanish national Universitary Free Software Championship 2014-2015, and it's a participant of the 2015-2016 edition and of the University of Granada Free Projects Championship 2015-2016. Future roadmap includes ARM support and a graphical HTML5-based GUI.
You can download NodeOS source code, build instructions, prebuild ISO images and contribute to its development at https://github.com/NodeOS/NodeOS (pull-request are highly welcome).