I have always encouraged companies to spend on great chairs, keyboards and multiple monitors for developers.  This was based on the conventional wisdom (among developers) that more screen real estate is better.

Recently, NEC sponsored a study that finds actual productivity benefits from using multiple displays.  The study was conducted at the University of Utah.  Ars Technica published a good overview and you can find a detailed summary
directly from NEC.  Interestingly, the study shows that there are diminishing returns to screen real estate and also that in some cases having one slightly larger screen (20’’) is better than having two smaller screens (18’’) combined.  The basic approach of the study – randomized assignment to different sequences of display size and random assignment to text editing and spreadsheet tasks – seems fine. 

It would be nice to see this study repeated with coding tasks. I have a nagging suspicion that large screens and multiple screens have some significant negative side effects on code quality.  In particular, I suspect that folks tend to write much longer code blocks when they have larger screens (both longer lines and more lines per function/method), which almost always translates into code that’s harder to understand and maintain.  I have no hard evidence for that, but these days the only time I have to play around with development is on long flights on my laptop, which enforces a nice discipline.