iloog is a Gentoo-based live CD targeted mainly at students and scientists. It features UnionFS filesystem support that enables you to write everywhere on the LiveCD and install extra packages, a graphical X environment through the Fluxbox window manager, many programming editors and IDEs, and a plethora of scientific applications, including Octave, Namd, Merlin, and full (La)TeX support.
CD Linux Server is an embedded Linux system on a bootable live CD. It can be used to set up mail, Web, file, FTP, proxy, DHCP, DNS, MySQL, LDAP, and other services very quickly. The mail server includes antivirus, antispam, and mail recorder features. It can be used for free for up to 10 accounts, while the advanced version is licensed for an unlimited number of users. There is not any restriction against the time.
btfs can be used as /init for constructing a run-time environment before running the real init. It supports extracting compressed (*.cgz, *.cbz2) and uncompressed (*.co) cpios located on a compile-defined directory (/). Also, it creates a tmpfs filesystem as the new root, if / isn't one already and the purpose of the initramfs isn't for starting a system in another location (disk, network, etc.). That will allow for the data on / to be swapped to disk when swap devices are activated later.
Cobbler is a network installation and update server. It can be used to automatically set up PXE, install virtual guests, manage answer files, and reinstall existing Linux machines. Advanced features include importing distributions from DVDs and rsync mirrors, kickstart templating, integrated yum mirroring (integrated with the installer to make updates available at install time), creation of netboot ISOs, and built-in DHCP/DNS Management. Tools such as "cobbler triggers", a Python API, and an XMLRPC API allow integration with cobbler with the rest of your datacenter environment or other systems management applications. There is also a Web interface to simplify management of the install server. Cobbler supports RHEL 4+, Fedora, and derivative distributions, and is also able to install other popular distributions.
PXE Knife is a tool for booting various floppy based utilities via syslinux, allowing them to be booted off a CD, a hard drive, or over the network via PXE. PXE Knife can be used with a number of commonly used tools such as hard drive manufacturer's utilities, memory testers, Linux recovery disks, Windows password changers, pre-configured PXE Knoppix booters (just add DVD), and a number of other utilities. It takes advantage of syslinux's menu system, so it's easy to navigate.
Gendist is a live CD generator system. It has nice features like multi-distribution CDs, support for grub, isolinux, and gfxboot boot managers, and a modules system for configuring your distribution in live mode. This system is independent from the kernel version (but need unionfs and squashfs support). It only works on Debian Sid or Ubuntu Dapper.
HeavenOS is an original, alternative 32-bit operating system for Intel 80386 compatible processors. It is made with NASM (The Netwide Assembler), and is not intended to compare to modern operating systems, but to try to get the best features and discover better ways to do things. It is intended to be a simple and pratical platform for development, running with a small amount of code.
Finnix is a small, self-contained, bootable Linux CD distribution ("LiveCD") for system administrators, based on Debian testing. You can use it to mount and manipulate hard drives and partitions, monitor networks, rebuild boot records, install other operating systems, and much more.