When I put together my original IKEA standing desk, I was still experimenting and wanted a solution where I could convert back into a regular sitting desk if necessary.
That solution worked well enough but it was never a long term solution. The biggest problem I had with it was that the computer screen was too far away from my face (the desk I used was 60cm deep) and I found myself leaning forwards to make out text on the screen. The desk was also pretty unstable and would begin to wobble if I was typing quickly.
So when I moved into my new home in late 2011, I began devising a more permanent and flexible solution. The result is this: a standing workstation made from an IKEA NUMERÄR countertop and an Ergotron LX Dual Stacking Arm.