DoudouLinux : Linux for kids.

DoudouLinux is a Linux distro meant for kids . It provides tons of applications that suit children from 2 to 12 years old with an environment as easy to use as a gaming console.  The project's version 1.0, code name "Gondwana", is now released.
Standard DoudouLinux is delivered with about fifty applications that have been specially chosen to be accessible for children from 2 years old. These applications cover the following topics:
Education - teach children while having fun.
Fun - have fun with games, easy to access but not necessarily simplistic
Work - write texts, calculate, communicate, etc.
Multimedia - listen to music, watch videos, play or create music, or create animation movies

Extremely Lightweight Linux : AntiX

AntiX is a fast, lightweight and easy to install linux live CD distribution which provides suitable information for old computers. It is based on Debian Testing and MEPIS for Intel-AMD x86 compatible systems. It should run on most computers, ranging from 64MB old PII 266 systems with pre-configured 128MB swap to the latest powerful boxes. 128MB RAM is recommended minimum for antiX. The installer needs minimum 2.2GB hard disk size. antiX can also be used as a fast-booting rescue cd. 128 MB RAM is the recommended minimum for antiX while the installer needs a minimum of 1.2 GB hard disk space. antiX can also be used as a fast-booting rescue CD.

Toorox Review

Toorox is a Linux Live-DVD based on Gentoo which uses KNOPPIX technology in booting. While booting, all necessary drivers will be included automatically (lshwd). It comes with lots of useful applications including system configuration tools, easy package management, and proprietary code installers. It compiles and install software from Gentoo sources. Toorox installation on your computer begin as a binary installation with all its advantages, such as fast, easy, and ready at boot, but subsequent package installation compiles source packages.

MoonOS - A feel of Mac OS X in Linux

MoonOS is a lightweight Linux distribution which uses the Enlightenment window manager and is based on Ubuntu/Debian, having a touch of the Mac's OS X.
According to MoonOS' official website, the focus of Moon is speed, low memory use, and attractive looks:
MoonOS' download is sizable, weighing in at 832MB, but the system requirements are very basic:

Scientific Linux 6.0 - A treat to scientific community.

Scientific Linux (SL) 6.0 produced by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN). It is the latest release of a Red Hat-based distribution specifically developed to meet the needs of the scientific computing community. This release is based on Red Hat Enterprise Linux (RHEL) 6.0 like CentOS, compiled from source.

REMnux : Distro for Malware Analyst

REMnux is another pentesting OS that you would like to have in your arsenal. Basically, it aids investigating malwares, so it's a very handy OS for malware analysts for reverse engineering malicious piece of software. The distribution is based on Ubuntu. Along with analysing malwares, it can also assist analyzing IRC bots, network monitoring, javascript deobfuscation, analyzing shellcode, memory forensics etc.

Fuduntu = [Fedora + Ubuntu]

Fuduntu is a perfect distro for those users who hate RedHat due to its complexities & less user friendliness. It is a distro developed to bridge the gap between Fedora & Ubuntu. It is a Fedora remix optimized for Netbook and other portable computers & may be regarded as the most attractive cousin of RedHat. Fedora mainly focuses on developers perspective whereas Ubuntu focuses on end user experience. Distros like Mint, Ubuntu are well versed with user needs & append it’s apps, but Fedora lacks such schemes. These are the pitfalls which are mainly taken care of in Fuduntu. Although, it’s in an incipient stage now, it has a good collection of default packages. It also needs to focus more on user needs.

Gnacktrack = [Gnome + BackTrack]

There is a new penetration testing Live CD in the market. It's called GnackTrack,  made solely for the Gnome lovers. GnacktrackR3 is based on Ubuntu 10.10. There are other penetration testing Live CD like BackTrack, DVL etc. BackTrack is the most well known name with in penetration testing community. Gnacktrack sounds like Backtrack but it's based on Gnome.
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Vinux : Linux For Visually impaired

Vinux 3.1 is has been launched which is a linux based on Ubuntu 10.10 meant for visually impaired users. It’s available in CD & DVD (USB & virtual version is yet to come) in both 32 bit & 64 bit version.  Vinux  has it’s own package repository, users can install packages using apt-get/synaptic & dedicated IRC channel. Beginner can press  (Ctrl+Alt+Q) to access Quick Start Guide.