This course gives a solid theoretical and practical foundation to standards based markup, covering such subjects as:
the theory behind standards
the correct use of structured markup: all the basic elements and attributes, including tables and forms
valid HTML and the validation process
accessibility
It's probably a bit basic for most people who've been on WSG for any length of time, but it's a great place to send any colleagues or friends who are starting out.
This is the full self-paced course usually sold online, available for free in weekly installments. The only limitation is that you have to keep coming back to the site every week to get the next section. It's a great way to really get the foundations of web standards right by spending just 5 or 10 minutes every week.