The Agile Work Roles article has been updated with more detail about all three roles and some additional commentary and links. This is a useful article to share with people who have already been introduced to agile methods, particularly if you are having trouble with a command-and-control management style (by management or team members).
The Waste vs. Value-Added article has an extended quote from the book Lean Six Sigma : Combining Six Sigma Quality with Lean Production Speed by Michale George as well as some new links. This article is very important for people who are looking at process improvements, lean, agile, or otherwise.
Update 20060608: added the second link!