The following are some good resources to check out:

The Linux Documentation Project is filled with quality resources such as:
  • HOWTOs: subject-specific help
    Guides: longer, in-depth books
    FAQs: Frequently Asked Questions
    man pages: help on individual commands
    Linux Gazette: online magazine
    LinuxFocus: multilingual online magazine

Sun has a in depth documentation area on their web page. They also have page for all your patches, knowledgebase search, and etc. One of the best pages they offer is their BigAdmin System Administration Portal. You can find shell commands, scripts, and even some linux support here. They also provide many other resources worth checking out.

Web GUI Software:
For those of you who are a little less tech savvy, check out Webmin. Webmin is a web-based interface for system administration for *nix (Unix/Linux). Using any browser that supports tables and forms (and Java for the File Manager module), you can setup user accounts, Apache, DNS, file sharing and so on.

Security Information:

A must visit site for security is CERT. They have a free mailing list you can signup for. They send out emergency bullitens concerning new security holes and vulnerabilities.

If you own a RedHat Server this is a must.

For those of you that run Windows servers stay up to date with whats going on by visiting Microsoft's TechNet Site (I recommend you signup for their free notifications if you run a windows based server.)

Looking for a good SSH deamon to install and client version for your PC? Check out SSH Communications Security. I have personally tested their ssh server software on both Solaris and Redhat7.3 and can verify it compiles under both of those operating systems.