The best security podcast ever. Hacking, security, and brews.
SANS. The leading source in security education.
Bruce Schneier's blog.
Spear phish your employees with the SPToolkit to educate them about malicious email.
David Kennedy, creator of the social engineering toolkit's website.
This site describes the perfect setup to wardrive and create a Google Earth view of the area driven.
Joshua Wright's wireless hacking website.
Network protocol analyzer.
The Information Systems Security Association (ISSA) is a not-for-profit, international organization of information security professionals and practitioners. It provides educational forums, publications, and peer interaction opportunities that enhance the knowledge, skill, and professional growth of its members.
Network forensics puzzles are hosted here every so often.
A good place to find upcoming "Capture the flag" competitions.
OWASP is an open community dedicated to enabling organizations to conceive, develop, acquire, operate, and maintain applications that can be trusted.
The DC3 Digital Forensic Challenge encourages innovation from a broad range of individuals, teams, and institutions to provide technical solutions for computer forensic examiners in the lab as well as in the field.