Distribution
- Archlinux.org
http://www.archlinux.org
a lightweight and flexible Linux® distribution that tries to Keep It Simple - Caldera
http://www.caldera.com
UNIX, Linux, and Volution - CentOS
http://www.centos.org
The CentOS Linux distribution is a stable, predictable, manageable and reproduceable platform derived from the sources of Red Hat Enterprise Linux (RHEL). - Corel
http://linux.corel.com
Corel supports the Linux community and is committed to developing products for the Linux operating system, including Corel LINUX OS, Corel's Linux distribution; WordPerfect Office, Corel's office suite; and CorelDraw, Corel's graphics suite. - Debian GNU/Linux
http://www.debian.org
Free OS Debian, Support, News, Distribution... - FreeBSD
http://www.freebsd.org
an advanced operating system for x86 compatible, DEC Alpha, and PC-98 architectures. It is derived from BSD UNIX, the version of UNIX developed at the University of California, Berkeley - Gentoo Linux
https://gentoo.org/
The website of Gentoo, a flexible Linux or BSD distribution. - Linuxmint.com
https://linuxmint.com/
Linux Mint is an elegant, easy to use, up to date and comfortable GNU/Linux desktop distribution. - Mandrake Linux
http://www.linux-mandrake.com
friendly Linux Operating System which specializes in ease-of-use for both servers and the home/office. It is freely available in many languages throughout the world - openSUSE.org
http://www.opensuse.org/
The openSUSE project is a worldwide community program sponsored by Novell that promotes the use of Linux everywhere. The program provides anyone with free and easy access to the world's most usable Linux distribution, SUSE Linux - Oracle Linux
http://www.oracle.com/linux
Oracle Linux with Oracle enterprise-class support - RedHat
http://www.redhat.com
is the destination for Linux, Embedded Linux, and open source solutions. We provide Linux-based support, documentation, downloads, training - Slackware Linux Project
http://www.slackware.com - SuSE
http://www.suse.com - Suse.cz
http://www.suse.cz