Curie is a very minimalistic, tiny C library. It supports basic I/O, basic networking, S-expression based I/O, signal handling, process handling, and I/O multiplexing. If the target architecture is explicitly supported, statically linked binaries may be as small as 4-20 kilobytes; if not, then it only relies on the host's C library. The library explicitly does not provide a POSIX interface so that it may be used in conjunction with a regular host libc (or without one).
Nuttx is a real-time embedded operating system (RTOS). It has a small footprint that is usable in micro-controller environments. It is fully scalable from tiny (8-bit) to moderate embedded (32-bit) systems. It also aims to be fully compliant to standards, to be fully real time, and to be totally open.
Endian Firewall is an all-in-on Linux security distribution that turns any system into a full-featured security appliance. It features a stateful packet inspection firewall, application-level proxies for various protocols (HTTP, POP3, SMTP), anti-virus support, virus and spam filtering for email traffic (POP and SMTP), content filtering of Web traffic, and a "hassle free" VPN system based on OpenVPN.
musl is a new implementation of the standard library for Linux-based systems. It is lightweight, fast, simple, free, and strives to be correct in the sense of standards-conformance and safety. It includes a wrapper for building programs against musl in place of the system standard library (e.g. glibc), making it possible to immediately evaluate the library and build compact statically linked binaries with it.
Linux is a clone of the Unix kernel, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance. It has all the features you would expect in a modern fully-fledged Unix kernel, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and TCP/IP networking.
ClearOS is an integrated network server gateway solution for small and distributed organizations. The software provides all the necessary server tools to run an organization including email, anti-virus, anti-spam, file sharing, groupware, VPN, firewall, intrusion detection/prevention, content filtering, bandwidth management, multi-WAN, and more. You can think of it as a next generation small business server. Through the intuitive Web-based management console, an administrator can configure the server software along with integrated cloud-based services.
m23 is a software deployment system for Debian GNU/Linux that allows you to install and administrate hundreds of clients via network. It can partition and format clients and install Debian, (K/X)Ubuntu, Linux Mint, Fedora, OpenSuse, and CentOS operating systems on your virtual and physical clients. Group functions allow the comfortable update and installation of further packages during operation. Mass installation functions simplify your administration chores. m23 has a Web interface. Backup functions are implemented for server and clients.
Papillon is a security module designed for the Solaris Operating Environment. It provides security mechanisms and protections that improve the overall security of the system by adding new functionality to the kernel such as a restricted proc, chroot environment protections, secure STDIO file descriptors, restricted symlinks in /tmp, setuid protections, and more. In the current version Papillon supports Solaris (8, 9, and 10) and OpenSolaris running on x86 and SPARC architectures in 32- or 64-bit mode.