links to other Linux resources

other Linux distributions

You should install different Linux distributions and then decide yourself which one fits best for your personal requirements. I recommend to look at the following distros:

Red Hat: This distribution is used by most people and there are several other distros based on it. Good security updates and generally sane packages. Contains not too many packages, so you have to look on their contrib server for missing ones.
Rawhide: Special development distribution from Red Hat. Installing a mixture between the last official Red Hat and some updated Rawhide packages should give you a nice server installation.
Debian: Contains really lots of packages and has nice scripts for the important configuration options. I personally don't want to trust those config scripts, but want to learn the config files myself. Debian is a very nice distro and definitely a good try. Very user friendly, though you also have to spend some time on special Debian things.
SuSE: Contains lots of packages and is very nice for a personal workstation to get your work done and see what packages are available for Linux. The installation and configuration tool YaST helps a lot.

sites with good documentation

Linux Documentation Project LDP: You should read through everything on this site at least once. It contains lots of general Linux documentation including books and other online infos.
www.linuxberg.org: This site has mirror sites all over the world and most of them contain the important Linux distributions.
Linux Weekly News: If you want to follow Linux development a bit more closely, you should read these weekly summaries. Excellent stuff.
www.uk.linux.org: Well maintained WWW site with good information.
KernelNotes.org: Good overview about kernel patches and kernel documentation.
www.linux-alpha.org: Very useful docu about running Linux on DEC Alpha machines. (Not online anymore?)

more official sites

Linux International: An organization for promoting the use of Linux.
www.linux.org: Linux portal site by Linux Online.
www.linux.com: Linux portal site sponsored by VAResearch.
OpenSource: the Open Source Definition

ftp-servers with big archives

ftp.kernel.org: Linux archive from Transmeta, Linus home site.
ftp.uk.linux.org: home site from Alan Cox, one of the big kernel developers.
GNU at the FSF: Home site of most GNU software together with the ftp servers ftp.gnu.org for official releases and alpha.gnu.org for test versions.
metalab.unc.edu: One of the largest software collections for Linux. If you search for smaller tools to get your work done, have a look on this site.
ftp.funet.fi: Used to be Linus home for new kernel versions and still has mirrors of important stuff.
tsx-11.mit.edu: Collection of many source packages for Linux.
ftp.gwdg.de: Big ftp-archive in Germany.

for German readers

general news from c't/iX/Heise
www.linux.de
www.linux-verband.de