Bookmarks

Windows

EventID.Net (information about the EventIDs in Windows' event log)
How to install and use the Recovery Console in Windows XP
Description of the Windows XP Recovery Console for advanced users
BOOT.INI and ARC Path Naming Conventions and Usage
How to read the small memory dump files that Windows creates for debugging
How permissions are handled when you copy and move files and folders
You cannot delete a file or a folder on an NTFS file system volume
Explanation of Regsvr32 usage and error messages
How to restore the system/boot drive letter in Windows
How to harden the TCP/IP stack against denial of service attacks in Windows 2000
How to prevent DNS cache pollution
Troubleshooting the Microsoft Computer Browser Service
Offline NT Password & Registry Editor
Unlocking Windows NT/2000/2003 Domain Controllers
Understanding Windows Server 2008 Core
Server 2008 Core Commands

Linux

Linux Standard Base
Filesystem Hierarchy Standard
The Linux Documentation Project
Linux From Scratch
RPM and DPKG reference

Mac OS X

Mac OS X keyboard shortcuts
Mac OS System Error Codes
"Well Known" TCP and UDP ports used by Apple software products
John DeTroye's Tips & Tricks
Platypus (a very handy little application that turns scripts into application bundles)
Command Line Mac
Setting up a Linux server for OS X clients

HP-UX

Software Porting and Archive Centre for HP-UX
HP IT resource center

Networking

An Illustrated Guide to IPsec
DNS for Rocket Scientists (an Open Source Guide to DNS and BIND)
Protecting Browsers from DNS Rebinding Attacks
Active FTP vs. Passive FTP, a Definitive Explanation

Computer Security

Help: I Got Hacked. Now What Do I Do?
Follow the Bouncing Malware, Part I
Follow the Bouncing Malware, Part II
Follow the Bouncing Malware, Part III
Follow the Bouncing Malware, Part IV
Follow the Bouncing Malware, Part V
Reflections on Trusting Trust
Schneier on Security: Changing Passwords
Schneier on Security: Write Down Your Password

Miscellaneous

Lorem Ipsum (dummy text generator)
lorempixum (placeholder image generator)
{placekitten} (lorem pixum with kittens)
Phrasen.com (German/English dictionary for phrases)
What the Font (font identification)
Identifont (font identification)
SelfHTML
Web Style Guide
Unix History (a timeline of the Unix operating systems family)
Graphical User Interface Timeline