Linux.com - For the community, by the community, Linux.com is the central source for Linux information, software, documentation, how-tos and answers across the server, desktop/netbook, mobile, and embedded areas.
The Linux Documentation Project is working towards developing free, high quality documentation for the Linux operating system. The overall goal of the LDP is to collaborate in all of the issues of Linux documentation.
Every Linux Fan Should Have One: Awesome site for reviews, tips and tricks. A magazine subscription is required to access all the content, but that is well worth it and the free content is excellent.