The goal is to be able to work on the laptop sitting, standing, kneeling, or lying down. Easily.
A little post on treadmill workstations by Neal Stephenson:
Sitting at a desk
For sitting I use my existing desk. I use an external keyboard and mice. Goldtouch keyboard wired and 2x Penguin mouse wireless. This stand, and these mouse platforms. Photo below. You can also use this setup to hold a larger external display for your laptop, if you put your laptop below. It's also good for larger laptops. I'm sitting on a buckwheat zafu, both for height and comfort. (I'm 6ft). I sometimes swap the chair for the yoga ball you see in the mirror. Sometimes I kneel or squat. I would like to try a kneeling chair. I wheel this to the foot of my bed to watch movies.
Sitting on a zafu on the ground
I use the same stand that I use for sitting.
For $280 the Zen office let's you do everything. Not sure about lying down.
This is obviously the one for me!
$187 just for the larger tilt seat:
with Blue lotus painted on top