Linux

FreeOS
Provides articles, documentation, links to software, and news about Linux and other operating systems.
http://www.freeos.com/

The Linux Counter
Get yourself and your computer counted among the Linux users.
http://counter.li.org/

Linux International
Non-profit association of groups, corporations, and others that work toward promoting and helping direct the growth of the Linux operating system and community.
http://li.org/

"Linux was invented here"
University of Helsinki - Department of Computer Science. Information about Linux and get the latest kernel versions and recent Linux kernel mailing list archives.
http://www.cs.helsinki.fi/linux/

Linux.com
A portal from SourceForge offering news, articles, and a "how to" knowledgebase.
http://www.linux.com/

What Is...Linux?
Definition of Linux and description of its history, relation to GNU and other UNIX systems, and links to related sites.
http://searchenterpriselinux.techtarget.com/sDefinition/0,,sid39_gci212482,00.html