Paul,
I am in agreement with everyone. I have been charged with developing new icons for my company's new software, and I have been using Photoshop for years to do so. After watching these videos and following your tutorials, I am well equiped to deliver some great icons. Thanks! I went right out and bought CorelDraw and Axialis IconWorkshop...
By the way, I have found that CorelDraw 12, and Axialis IconWorkshop are a great combo for creating great icons. I have used a lot of different programs to create icons, and so far I'd say this combo is the best.
My vote goes for an advanced mesh tool lesson, and perhaps some intro lessons on perspective and 3D (extrude), and the contour tool would be great as well.
Thanks Again!