I've taken computer security (infosec) classes at City College of San Francisco, aka CCSF, including Intro to Network Security, Ethical Hacking, Computer Forensics and Malware Analysis. It's a topic I constantly find intriguing and also one that's constantly changing. There is voluminous amounts of InfoSec information available online. This list is by no means complete or even close to that but instead are filled with resources I've found to be most useful.
There are lots of infosec blogs around. Here are some of the best ones.
Schneier on Security - One of the most renowed infosec experts in the world. His books on cryptography are considered the best around.
COMPTIA - Offers certification in many areas, like A+, Network+, and Security+.
ISC² - Offers security certification programs for CISSP, CSSLP, and others.
SANS Institute - Offers computer security training via conferences, online and onsite.
Hacking Exposed Computer Forensics Blog
Windows Incident Response Blog
SMART - Linux forensics tool.
Here are some tools to fight back with.
John the Ripper - Password cracker. Handy tool if you get logged out of a root or administrator account and need to log back in.
KALI Linux - Another Pen testing tool.
Kismet - Wireless detector, sniffer, and intrusion detection system.
Metasploit - Pen testing software
NMap Security Scanner - Open source utility for network exploration or security auditing.
Ultimate Boot CD - Diagnostic tool
Wireshark - Network sniffer.
Bay Area Hacker's Association - Local infosec mailing list.
BSides - Infosec cons that take place at locations near where a big security conference is going on. BSidesSF is one example.
DEFCON - Huge hacker conference that takes place every July.
Hacker Dojo - Bay Area "hacker" community center.
OWASP - Non profit InfoSec group with chapters worldwide.
samsclass.info - Home page for Sam Bowne, a CNIT instructor at CCSF. He has slides from his various classes here, along with countless links to other infosec pages.
Uribe100.com - Felix Uribe's list of the Top 100 cybersecurity web sites.