Working with a lot of PDFs, Word and Publisher documents and various IDEs can be difficult on landscape monitors, however mounting a monitor in portrait orientation can be expensive when you don't want to drill into the wall as the cheapest desk mounting VESA mount I found was still around £40-50, which was a little over my budget.
So I designed a simple stand which was easy to make using parts left over from one of my other projects.
Step 1: Prepare Your Monitor
Firstly, this works best with monitors which have the VESA mount directly in the centre, if it is towards the top of your monitor then it is likely the manufacturer doesn't want you to use it in portrait (I'm guessing cooling related as the monitors I have seen like this produce a lot of heat, and using a monitor in portrait orientation reduces the convectional airflow through the monitor, as the vents are on the top and bottom).
Next you want to remove the stand from your monitor, this can take a lot of brute force, but it's always best to check with the manual in case there are some little catches you may have missed, in my case even after I had removed the stand there was still a part of the hinge sticking out from the side, but I think I can live with it.
I am lead to believe that some monitors will also allow you to rotate the on screen display for using it as a portrait monitor, I haven't been able to find this option on my monitor, but it isn't often I use the OSD on my monitors anyway.