I know at least one workplace where they use desks that can be adjusted to a standing or sitting position. If you feel like standing, you stand. If you prefer sitting, you sit. Isn't this the best of all worlds?

I tend to find the reclining & feet up posture described near the end the most comfortable for me, though it also tends to make me drowsy. Ergonomics "experts" however have told me again and again that the sitting upright position is the best for my back, which seems to contradict this article.