I am a big fan of screencasts –
The Blogcast Repository, and other sites like it provide a rich learning experience for IT Professionals and the curious alike. And I have found that a demonstration is so much more powerful and aides dramatically in the retention of the subject matter. So as Microsoft has been embracing screencasting and adding more and more content, I have been very happy indeed!
Here is an excellent series on Microsoft Office Development – a topic which IMO lends itself beautifully to screencasting.