Web Worker Daily has a good post on the value of using multiple monitors. With several applications open, I do find myself rooting through my desktop just as I do for a piece of paper on my desk (meaning same level of frustration). Where's the spreadsheet (better, which spreadsheet was it), why can't I click back into Word (idiotically left FIND open but can't see that because I'm copying something off a web page), which tab do I need on the browser (oh, off the screen)...I could put an end to all this if I simply used both the monitors on my desk, leaving work fully open across the screens. Duh.
PS: First time I saw serious numbers of monitors in people's offices was at Apple's R&D campus in Cupertino, California. Like six. Or eight. I never saw an office with only a single monitor. That was 1995. By now, they must have wraparound screens covering all walls.