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.
G4L is a hard disk and partition imaging and cloning tool. The created images are optionally compressed, and they can be stored on a local hard drive or transferred to an anonymous FTP server. A drive can be cloned using the "Click'n'Clone" function. G4L supports file splitting if the local filesystem does not support writing files larger than 2GB. The included kernel supports ATA, serial-ATA, and SCSI drives. Common network cards are supported. It is packaged as a bootable CD image with an ncurses GUI for easy use.
Slackware is the longest-running distribution of the Linux operating system. Slackware offers a stable and secure version of Linux that is perfect for home, office, or educational use. Slackware is easy for beginners to install, but contains all the advanced features required by the experienced UNIX power-user.
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.
Recovery Is Possible (RIP) is a CD or USB boot/rescue/backup/maintenance system. It has support for many filesystem types (Reiserfs, Btrfs, Ext2/3/4, HFS+, ISO-9660, Squashfs, UDF, XFS, JFS, UFS2, CIFS, MS DOS, NTFS, and VFAT) and contains several utilities for system recovery. It also has IDE/SCSI/SATA, RAID, LVM2, and Ethernet/Wireless network support.
Briefly, FreeBSD is a UNIX operating system based on U.C. Berkeley's 4.4BSD-lite release for the i386 platform (and recently the alpha platform). It is also based indirectly on William Jolitz's port of U.C. Berkeley's Net/2 to the i386, known as 386BSD, though very little of the 386BSD code remains. A fuller description of what FreeBSD is and how it can work for you may be found on the FreeBSD home page.
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.