Don't get me wrong, I am an HTML geek, myself.  I'm a huge advocate for well-formed, semantically-appropriate HTML in the development of web pages.  I think HTML can be a powerful tool. That said, I think the need for people seeking to publish to the Web to know HTML is on a rapid decline.

I had seen data visualization of this caliber a couple of years ago.  It is the presentation of data, animated over time.  It is a very powerful way of visualizing trends in three-dimensional data that is otherwise impossible to detect in two-dimensional charts.  Consider Now, Google makes this sort of presentation freely available via Google Docs.