Owl (Openwall GNU/*/Linux) is a small security-enhanced Linux distribution for servers. Owl also makes a good base system for customized virtual machine images and embedded systems, and Owl live CDs with remote SSH access are good for recovering or installing systems (whether with Owl or not). A single Owl CD includes the full live system, installable packages, the installer program, as well as full source code and the build environment capable of rebuilding the entire system from source. Owl supports multiple architectures (x86, x86-64, SPARC, and Alpha) and offers some compatibility for packages developed for other Linux distributions. The primary approaches to security are proactive source code review, privilege reduction, privilege separation, careful selection of third-party software, safe defaults, and "hardening" to reduce the likelihood of successful exploitation of security flaws.
The Objex Project (like the GNU Project) aims to develop a complete operating system composed of free and open source software. In contrast to the GNU Project, it aims to build a modern system that brings together all the recent advances in computer science, instead of a Unix-like system. "A complete system" means that it will include the kernel, a full suite of developers tools, user utilities, and a graphical user interface. It is based on OSKit, a framework and a set of utilities, drivers, and program code intended for operating system creation.
joeq is a Java 2 (JDK 1.3 and 1.4) compatible virtual machine. It is unique in that it is entirely implemented in Java, leading to greater reliability, portability, maintainability, and efficiency. It is also language-independent, so code from any supported language can be seamlessly compiled, linked, and executed dynamically.
openMosix is a a set of extensions to the standard Linux kernel allowing you to build a cluster of out of off-the-shelf PC hardware. openMosix scales perfectly up to thousands of nodes. You do not need to modify your applications to benefit from your cluster (unlike PVM, MPI, Linda, etc.). Processes in openMosix migrate transparently between nodes and the cluster will always auto-balance.
JTMOS stands for "Jari Tuominen's Minimal Operating System". The JTMOS operating system project aims to create a fully functional multitasking x86 operating system. It primarily targets low-end systems with small hard disks, preferably i586 family or newer. Currently focus in the project is on communication, TCP/IP stack, and building up FAT file system support. JTMOS mimics some features from Linux-style operating systems like the root directory system. JTMOS can already boot up from DOS, or independently from hard disk or floppy disk with its own custom bootloader.
EV-OS is an operating system which runs in real mode on the x86 platform. The system must be booted and run from floppy disk. The user interface is command-line based. Application programs must be prepared for operating system. EV-OS application programs can be developed under the Windows operating system, and a special tool is used to transfer files from Windows to EV-OS. EV-OS is written in assembly and the transfer program is written in C. The downloadable package contains an executable image file, the source code of the operating system, and some installation documentation.
SOSSE (Simple Operating System for Smartcard Education) is a free smart card operating system. It is implemented in C and assembler for the Atmel AVR smart cards (Funcard, PinkCard, Jupiter). The aim of this project is to provide something like Linux for smart cards, which is a market full of NDAs. SOSSE should make it possible to learn about smart cards, and to implement and test your own ideas.