The 64 Studio Platform Development Kit (PDK) is a version control system for GNU/Linux distributions, allowing the creation and management of many different projects, based on Debian and Ubuntu sources. PDK is written in Python, and the source code is well commented and contains documented examples.
CinayOS is a 64-bit operating system that was forked from Linux in order to develop a radically different approach to concurrency, SMP, and most other kernel subsystems. Its goals include a new caching infrastructure, easy software package management, and an OpenGL accelerated animation system.
The Familiar Project is composed of a group of loosely knit developers all contributing to creating the next generation of PDA OS. Currently, most of our development time is being put towards producing a stable, and full featured Linux distribution for the Compaq/HP iPAQ series of handheld computers, as well as apps to run on top of the distribution.
GNUSTEP Live CD contains a lot of software for GNUstep, a free implementation of the OPENSTEP framework (which is also directly used in Mac OS X as Cocoa). It includes excellent applications for RAD (GORM and ProjectCenter). The CD is available for i486, AMD64, Apple Mac PowerPC, and Sun UltraSPARC computers.
GeeXboX is a standalone media player Linux distribution, similar to MoviX. It's a small bootable CD that allows you to play your favorite video (DivX, XviD, H.264, MPEG 1/2, VCD, DVD, OggMedia, Windows Media, RealMedia, etc.) and audio (MP3, Audio CD, Ogg Vorbis, FLAC, MPC, etc.) files. It also supports networking, and is able to play media from Windows/Samba share, NFS, UPnP A/V Media Servers, RTP/RTSP servers, or SHOUTcast. It supports TV-out, TV tuners, DVB cards, and WiFi cards. It is based on MPlayer, and can be used on any x86, x86_64, or PowerPC computer. It's easy to modify the source to build your own GeeXboX or use an alternative boot method.
ROPE is an open-ended iptables match module that allows rules to be written using a simple but powerful scripting language. It is designed for controlling complex high-level protocols that cannot be blocked using traditional criteria based on port numbers (etc.). Criteria can include tests on any field of the IP, UDP, or TCP headers as well as the packet data payload.
Kerrighed is a Single System Image operating system (SSI) for clusters. It offers the view of a unique SMP machine on top of a cluster of standard PCs. The goals are high performance of applications, high availability of the cluster, efficient resource management, high customizability of the operating system, and ease of use. It is implemented as an extension to Linux operating system (a set of Linux modules and a small patch to the kernel).