It's not just about monitor placement though. Keyboard height, at least for me, is more important for a comfortable computing environment that monitor height.
Just checking now, I've got about 18-inches difference between my seated keyboard height and my standing keyboard height.
Interesting. I actually appreciate the low standing keyboard height in my setup. My setup is far from ideal, but does have some advantages.
META: why is my 5 ranked post at the top? There's more interesting posts more highly ranked further down. Because it has more comments? To those who care, I think `javan`'s post is the most relevant for somebody looking to make a cheap & easy desk.
If you think you need more than 12 inches you're slouching while you're sitting.