Drupal theming with the 960 grid system by Todd Ross Nienkerk. General overview of the 960 grid system. covering basic terms and simple implementation.
Part 8 of 9 in the series of the Basics of Drupal 6, this tutorial will show you how to download, install, and enable themes that you can use to customize the look of your Drupal website.
Bending Zen - Subthemes is the second video from my Bending Zen Series. This shows you how to quickly set up a subtheme using Zen as your base theme in Drupal 6.