INX

I stumbled across an incredibly useful tool the other day, which I thought I'd share with you. INX is a custom Ubuntu respin that lacks an X window server. In other words, it's a command line only system.
Now, this may at first make you think "meh, what can that do?", but INX sets out to prove you wrong by letting you do virtually everything you can do from a GUI! Including browse the web graphically, read email, listen to internet radio even watch videos!
INX is two things: First of all, it's a great demonstration of just how much you can actually do from the command line. Second, it's a great learning aid. It includes loads of tutorials on how to use the command line. I learned a load of things from one go, including how to use GNU Screen.
If you're even remotely serious about learning to use Linux properly, I highly recommend grabbing a copy from the link above!