I honestly believe that worker productivity is improved with more screen real estate. A report by Pfeiffer Consulting sponsored by Apple has benchmarks on performance with and without Apple's 30" Cinema display. The PDF of the report is available here.
Computer World looks at the report and say that "other experts say those conclusions are wrong, arguing that the productivity improvement estimates are too high and that using two monitors side by side would likely be a better productivity booster than one larger monitor."
I know Danny lives and dies by his 3-monitor setup.
I personally have one 23" Apple Cinema Display. To be honest, there are actually times where I wish I had more space or a second monitor. I use a MacBook Pro which is on the right hand side of my monitor.

I can open the monitor of the MacBook Pro and use a dual screen mode. But I tried it out and I didn't like it. They have to be the same size and side by side to work properly.
Ronnie, brother and partner at RustyBrick, uses two 19" older Apple Cinema displays side by side. He loves it.
Our RustyBrick designer, "Skew," uses two 20" Dell high-def LCD monitors side by side. He lives by it also.
Then the rest of the guys are on LCDs typically 19". One hooked up a CRT and an LCD to his computer.
Oh, when I just use the laptop's screen, while at home or traveling, I am always crunched for space.


Comments
Barry - I always make sure everyone has a least the Dell 24" widescreens, and our programmers get two side by side - 4ft. of screen real estate may be overkill, but even if it increases productivity only a little, it's totally worth the $600 a shot.
Posted by: randfish | October 13, 2006 7:10 PM
I could not live without them...
My main clients office has now got dual screen on every PC and it make a difference..
The sale guys use excel in 1 window and notes in the other.. Perfect.. You can upgrade for about £250 about $500 for a smallish screen..
Go for it ;)
(xmas bonus ? )
Posted by: Gabs | October 16, 2006 4:57 AM
I'm on XP systems, but ....
I have 2 of the Dell 2407wfps - I got them for $689 each w/free shipping using a coupon code and other little bonusy things I found. All I can say is my day is far, far more productive than it was with the two 20s I had before. These are incredibly sharp monitors.
I use them with software that allows me to mouse between computers called Desktop Rover. I also have another machine running a 17" Dell monitor at lower res for testing style sheets to be sure my site development works for the masses. :)
Posted by: Scott Clark | October 18, 2006 8:52 AM
I'm on XP systems, but ....
I have 2 of the Dell 2407wfps - I got them for $689 each w/free shipping using a coupon code and other little bonusy things I found. All I can say is my day is far, far more productive than it was with the two 20s I had before. These are incredibly sharp monitors.
I use them with software that allows me to mouse between computers called Desktop Rover. I also have another machine running a 17" Dell monitor at lower res for testing style sheets to be sure my site development works for the masses. :)
Posted by: Sclark | October 18, 2006 8:53 AM