Learning Command Line Fu

I recently found INX which is a live cd linux distribution designed for learning about the command line. INX stands for 'is not X', which means X, the basis upon which graphical user interfaces rest, isn't on the cd. There's always access to a console, though, and there are a series of tutorials. I'm finding interesting, anyway, especially since I like to see what I can do with old or discarded hardware that nobody else has a use for.