Wait, what do you put on top of it to hold the (presumably) laptop? I say 'presumably' as you usually need two heights on standing desks: one for the keyboard and one for the monitor which should be higher.
My main desk is actually a drop leaf table. I sit my desktop PC on it. When sitting, the monitor is placed in front of the PC. When standing the monitor goes on top of the PC, and I drop the desk bit.
Something like this: http://janeharrop.co.uk/images/12thimages/12th_utility_drop_...
I'd actually prefer a drop leaf that I could hide the PC in. But currently the PC serves as a good stand for the monitor. It also makes the PC very accessible. The trickier part of my setup is accommodating a mouse. But I could just place a board on the piano/keyboard stand.