(Maga)Zines:
2600 Magazine
Off the Hook, Phrack, HOPE, hacked sites, hackers in the media
The Happy Hacker
Guide to (Mostly) Harmless Hacking, Hacker Wargames, Happy Hacker Digest
Linux (Lih-nucks):
The Linux Documentation Project (UNC)
Tutorials, HOWTO's, man pages, and the HTML Linux Source Navigator
The Linux Home Page
Distributions, applications, documentation, Linux in the media
Red Hat
Home of Red Hat Linux
rpmfind.net
RPM database, downloads
Linux Mailing Lists
Large list of Linux Mailing Lists including HTML based subscription
News:
Wired News
Industry news (Updated several times daily)
ZDNNews
Ziff-Davis (PC Week, ZDTV, etc.) the people who bring you COMDEX.
AntiOnline
Hacker News
Request for Comments (RFC):
Ohio State (FTP) or
Ohio State (HTTP)
Ohio State's archive of RFCs
Hyperlinked RFC Index (faqs.org)
Home of the Usenet FAQ archives
Advisories:
Computer Emergency Response Team (CERT)
Advisories, Alerts, Reports, Tech Tips
Computer Incident Advisory Capability (CIAC)
Virii and virus hoaxes, chain letters
Rootshell
Advisories, exploits, hacked site news
Bugtraq Archives
Bugtraq mailing list archives - UNIX security
Humor:
User Friendly
Online comic strip set in an ISP
Miscelaneous:
The DEF CON Homepage
Info on DEF CONs past and future, lots of links
L0pht Heavy Industries
L0pht products, texts, news