For full disclosure: I work for Ergotron and we make all kinds of computer mounting solutions, including stand-up workstations (those are my arms in the photo at left).
It is a very simple equation: standing a little more each day burns extra calories, tones muscles, improves posture, increases blood flow and ramps up metabolism.
On the creative side, being freed from a "desk-sentence" (I can't take credit for that reference to "death sentence" I read it on a blog)... where one is usually hunched over and stuck in one place, and then freed to stand and move around sharpens the mind and creative juices. I can't fully explain it but you have to try it... I have, and I love it.
The standing workstations that Ergotron makes allow the user to stand or sit so if you get tired you can still sit. I think this form of standing while you compute is going to catch-on big in ad agencies and in corporations... we are receiving an enormous amount of positive feedback at Ergotron saying how standing at work is improving their health and productivity.
