EnableBigLBA - Enable support for large hard disk greater than 137GB. (Win2K and XP)
Cleanup spywares/malwares using sysinternals
Windows Key shortcuts
Windows keyboard shortcuts - more from Microsoft
Copy messagebox text to clipboard

Windows XP
Disable And Remove Thumbs.db In Windows XP
Speedup Windows XP boot time. (XP)
Devils own Key for  XP.

Vista
Bigger Thumbnails for Vista’s Alt-Tab

Enable syntax highlighting in vim
keyboard shortcuts and settings for vim
sed one liners
awk one liners
perl one liners
The most common linux attacks
Access windows share from linux
simple HOWTOs
How to safely connect from anywhere to your closed Linux firewall - knockd
Disable (or enable) CTRL-ALT-DEL for reboot.
To check the version:
    $ uname -a             # kernel version
    $ lsb_release -a      # distro info
    $ cat /etc/issue

Ubuntu
Set Backspace's Firefox behaviour
Keyboard shortcuts - Customize
more keyboard shortcuts - and more
Make GNOME menus faster.
Disable IPv6 to speedup Ubuntu
Reduce swapping
10 Tips for Ubuntu
Tips to secure Ubuntu server
Reset root password

20 Search tips
Simply Google - de-googlized
keyboard shortcuts for gmail