Learn to code, interactively, for free

"When human beings acquired language, we learned not just how to listen but how to speak. When we gained literacy, we learned not just how to read but how to write. And as we move into an increasingly digital reality, we must learn not just how to use programs but how to make them."
The opening lines to Douglas Rushkoff's book Program Or Be Programmed.

On his blog, Daniel points to Codecademy, a website you can use to "learn to code, interactively, for free".  I have tried it.  It is a great resource.

www.codecademy.com