A Taste of Linux - Jim Lynch bites into four low-fat distros that boot off CD but deliver the full flavor of Linux. Use Linux on your computer without ever installing a thing. - http://www.extremetech.com/article2/0%2C1697%2C1457025%2C00.asp
Server optimized Linux diagnosis - Diskless Linux-distribution, which was designed for diagnosis and rescue of almost any operating system that runs on i686-based hardware. - http://www.sol-linux.com/
List of Linux Live CDs - Extensive tabular listing. Shows name, size, and primary functions. - http://www.frozentech.com/content/livecd.php
stresslinux - minimal linux distribution running from cd-rom or PXE to stress your entiry system and monitoring the health. - http://www.stresslinux.org
Damn Small Linux - A business card size (50MB) Linux distribution; with description and download links. - http://www.damnsmalllinux.org/
Morphix - A modular distribution without any configuration; comes with live-cd support. - http://www.morphix.org
Virtual Linux - Bootable Mandrake Linux distribution with 1.6 gigs worth of tools and toys on a single CD. - http://sourceforge.net/projects/virtual-linux
Dyne Bolic - Complete GNU/Linux operating system working without the need for any hard-disk. - http://lab.dyne.org/DyneBolic/
DemoLinux - Dedicated to bootable Linux CD distributions. - http://www.demolinux.org/