This is my list of year-2005 top Linux, UNIX and open source related web sites. The following sites are highly recommended for Linux/UNIX admin.
Linux Documentation Project
The best place to look for Linux documentations, howto and guides.
URL: Linux Documentation Project
A wide variety of documentation is available for FreeBSD
URL: FreeBSD documentation.
IBM developerWorks Linux section
URL : IBM developerWorks
It includes articles and Howtos on Linux, BSD, Apache, Sys-admin, Perl and other interesting topics.
URL: O'Reilly Network
It is online Linux magazine (a member of the Linux Documentation Project). Publish an excellent set of articles and howtos.
URL: Linux Gazette
It is dedicated to Linux (includes BSD/Solaris section too) and Mobile Computers.
Include articles, howtos, and product reviews for embedded Linux devices
It is a web community devoted to sharing the latest in kernel development news.
It picks up the best of articles related to Linux/BSD/Sys admin
O'Reilly's Electronic Safari Bookshelf
It's an online, searchable library of over 2000+ computer books. It includes books from many good publishers. And best part is subscriptions are quite affordable. Try out their two-week free trial.
URL: Safari electronic bookshelf
Google Usenet groups
Search for Linux, BSD, Solaris, Shell scripting, Perl and much more
URL: Google groups
Linux and Open source related hot discussion and news