I had a lot of geek friends sign up for last Fall's free courses from Stanford University, so when I saw this Computer Science 101 course being offered in February I thought it would be great to do with my 14-year-old son. Stanford is doing several classes like this. You can find a complete list at the bottom of the page linked below.
CS101 teaches the essential ideas of Computer Science for a zero-prior-experience audience. Computers can appear very complicated, but in reality, computers work within just a few, simple patterns. CS101 demystifies and brings those patterns to life, which is useful for anyone using computers today.
In CS101, students play and experiment with short bits of "computer code" to bring to life to the power and limitations of computers. Everything works within the browser, so there is no extra software to download or install. CS101 also provides a general background on computers today: what is a computer, what is hardware, what is software, what is the internet. No previous experience is required other than the ability to use a web browser.