Slackware Linux
The Official Release of Slackware Linux by Patrick Volkerding is an advanced Linux operating system, designed with the twin goals of ease of use and stability as top priorities. Including the latest popular software while retaining a sense of tradition, providing simplicity and ease of use alongside flexibility and power, Slackware brings the best of all worlds to the table.
SmartOS
SmartOS is an open-source UNIX-like operating system based on illumos, a community fork of OpenSolaris. It features four technologies - ZFS (a combined file system and logical volume manager), DTrace (a dynamic tracing framework for troubleshooting kernel and application problems), Zones (a lightweight virtualisation solution), KVM and bhyve (two full virtualisation solutions for running a variety of guest operating systems, including Linux, Windows, BSD and Plan9).