Unsure what a Linux distribution is? Read the Linux Distribution Guide
Ubuntu Privacy Remix
Ubuntu Privacy Remix is a modified live CD based on Ubuntu Linux. UPR is not intended for permanent installation on a hard disk. The goal of Ubuntu Privacy Remix is to provide an isolated working environment where private data can be dealt with safely. The system installed on the computer running UPR remains untouched. It does this by removing support for network devices as well as local hard disks. Ubuntu Privacy Remix includes TrueCrypt and GnuPG for encryption and introduces "extended TrueCrypt volumes".
ULTILEX stands for "Ultimate Linux Experience". This is a live Linux CD compilation which in turn contains several live Linux distributions. You can boot ULTILEX from CD/DVD and USB flash devices.
ValEnt Linux uses the KDE desktop environment, it has all the necessary software pre installed for: writing documents, spreadsheets, presentations, image manipulation, playing DVD's and music, viewing PDF files and much more. ValEnt Linux also has the synaptic software manager installed.
Virtual Linux is basically the Mandriva Linux operating system, modified to run directly from your cd rom drive. With Virtual-Linux 1.1 you get about 1.6 gigabytes of software, all compressed onto one cd rom, using cloop compression.
Xebian is an Xbox-enabled version of the Debian GNU/Linux distribution. It is based on the standard x86 Debian, but the install process, and naturally the bootloader, the kernel and the kernel modules are all customized for the Xbox.
XFCELive is a community-based effort to bring the distro and desktop environment closer together.