Dual Monitors - Vanity or Productivity Booster?

For quite some time, I noticed that some people that I considered very "techie" had two or even more than two monitors.  To be honest I felt that it was just a bit ostentatious. Then for some reason (I can't remember exactly how right now), I came into possession of two LCD monitors.  I decided to use both of them since I had the desk space.  I must say that I have fallen in love with using two monitors and I apologize to all those anonymous folks that I thought were just being vain.  Two monitors is truly a productivity booster.  At one time I would have thought that having two windows open at the same time on one monitor was great, but that was before I started using the two monitors. There are a number of circumstances when it is especially useful to have two monitors.  One such circumstance is when you are trying to follow some complicated instructions.  Open the file containing the instructions, slide it to one monitor and use the other monitor to follow the instructions.  Another circumstance might be when you have two instances of the same program open.  I regularly use BOTH Chrome and Firefox as browsers.  Chrome is set to be on my extended monitor, Firefox on the other.  Works GREAT!