I really like what the chaps at CommonCraft are doing with their series of Web 2.0 tutorials.
Simple, to the point, well-written and entertaining, they cover most of the bases in an easy to follow, informative style.
They even do language translation, and offer transcripts, so a throughly good show all round.
Every Marking Director wanting to lean more about how the web works nowadays, or indeed who wants to bring employees up to speed, would do well to subscribe to these little beauties:
You can also see neat little tutorials on rss and wiki's here: