How to expand a VDI disk image on a Macintosh computer: http://mithunme.wordpress.com/2013/07/08/how-to-increase-the-disk-size-of-a-ubuntu-vdi-on-mac/. This would also be applicable to a Linux machine. A very useful tip.
How to add a standard user to the /etc/sudoers file on a Macintosh computer: http://mithunme.wordpress.com/2013/02/10/adding-a-standard-user-to-etcsudoers-in-mac-os-x/. This is also applicable to a Linux machine.
How to install World Of Warcraft on Ubuntu 13.04 using Play On Linux.
How to reset your Ubuntu password using the recovery console.
Misc Firefox tips and tricks.
http://forums.mozillazine.org/viewtopic.php?t=170970.