Every once in a while there comes a situation where a file is too big for a CD, or you want to store a file larger than 2GB on a FAT partition, or you want to make a backup of data with UNIX-style permissions (almost a 100% necessity if backing up a $HOME folder with settings) and all you have is a FAT volume somewhere. Here the multi-volume feature of GNU tar comes to play. The ZIP and RAR formats have a similar feature, probably originally for floppy disks, but they don't store UNIX-style permissions. Also, the feature is in GNU tar for a partly historical reason (partly because it is probably still widely used for the original purpose):

Did you know that you don't necessarily need flash to view YouTube videos? You don't actually need to even visit YouTube to be able to watch a cool video that a friend gave you a link to.

In Bash, when (possibly) dealing with a variable that contains a filename, be sure to doublequote it.

Tor is a toolset which helps anonymize ones self online. It's useful if you wish to keep your activities online anonymous.

After starting to read 'Database Nation: The Death of Privacy in the 21st Century' I've become more aware of how easy it is to have privacy violated, and it's effects on society.

If you find text on a website too small to read in FireFox you can increase the font size by using Ctrl and '+' on the numpad. This will only effect the tab you are currently in, and you can revert with Ctrl and '-'.