Salvare (from the Latin "to rescue") is a small Linux distribution designed for small, credit-card sized CDs which typically hold around 34MB. More Linux than tomsrtbt but less than Knoppix, it aims to provide a useful workstation as well as a rescue disk. In addition to providing a rescue environment similart to tomsrtbt, it adds OpenSSH, a graphical and text mode Web browser (Links), security tools such as chkrootkit, nmap, and tcpdump, the ability to apt-get install additional software from Debian into tmpfs, the ability to run entirely from RAM, and much more. It's also customizable using a simple source-code based package management system.
PlumpOS is a bootable openMosix node on a CD. Pop the CD into a 486+ computer and you have an instant openMosix node. It supports loading 3rd-party packages and adding custom kernels. It takes up very few resources. It was originally a clone of clump/os, but has evolved into something that doesn't resemble it much anymore.
VoiceBuntu (formerly Ubunterisk) is an Ubuntu-based live CD that uses Asterisk and VoiceOne to provide VoIP service without any system installation process. VoiceOne is a Web-based GUI for the Asterisk PBX. Ubunterisk can be used as a phone client as well as a PBX server. Ubunterisk can be administered either remotely or by accessing its local GUI. A capser-rw filesystem is used to store the system's data persistently.
TurnKey Drupal is an extremely easy way to get up and running with Drupal in just a couple of minutes. It's a pre-integrated turnkey server based on Ubuntu that is packaged as a Live CD image capable of supporting installations on both physical and virtual machines, including VMWare, Xen, VirtualBox, and KVM. It features a small footprint, automatic security updates, a rich Web administration interface, and an easy to use configuration and installation console. It includes a dozen popular Drupal extensions for convenience.
MBCD (MultiBootCD) is a shell script to make a customized CD-ROM that can boot any kind and any number of image files. Currently, 4 types of images are supported: floppy images (1.2M, 1.44M, or 2.88M), Knoppix-like images, kernel-binary images (e.g. memtest86), and the Windows XP Recovery Console.