I only have room for single mon setup, but I would prefer dual monitor.

I think dual setup is optimal for things like photoshop.

Triple would be best for driving sim or anything first person view-ish.

You left off options for those who don't have single small. I have single large, never really experienced dual....so can't comment on it. I could potientially pull it off. 

I should add "usually". Doesn't mean it has to be specific size.

I use a 23'' wide screen at home and wanted another one. But there's just no room for my small desk in my small room in my small home.

Single 13" laptop, with 5 multiple desktops.

Dual is pretty awesome. I can't even imagine how I lived without it for so long.

Only drawback, I have two totally different kinds of monitors. 18" CRT and 24" LCD.

Looks a bit weird, but still very useful.

The electricity bill from that one can buy you another 24'' in a year, LOL.

ha true, but I don't need to pay such bills yet. Well until summer at least when I move out and get my own apartment :)

It's just my secondary monitor anyway, so it's usually turned off when I'm just browsing the internet or watch a movie etc.

"Only" use it when I need some more space on my screen or when playing PS3/360 on my main display, so I can chat or watch some Simpsons episodes while playing without having to change the input signal.

Studies have shown that it is not the size of the monitors, nor the amount of monitors, that increases your productivity, but the amount of pixels.

Edit: Source, it links to the studies themselves too:

http://infovegan.com/2010/08/18/manage-pixels-not-monitors

Dual monitors is the way to go, though now I have three at work and it's so nice too.

I recently finally got The Wife to use two monitors and she doesn't ever want to go back either. Even just for browsing and anything casual it's the far better setup.

It really depends on the person I think.  I could have a monitor with an insane amount of pixels but it doesn't change the fact I like things full screen when possibl.e

My current work setup, I have my main monitor with my editor, Max, and Photoshop running fullscreen (I rarely have to use any of those more than one at a time), my right monitor has Outlook and Firefox running fullscreen, and my left monitor has iTunes full screen.

I do have some thing that aren't full screen and those are from my editor.  On my left screen I have my debug console and information running over iTunes and on my right monitor I have my script window and some other information runnign over Outlook.

With all the pixels in the world I couldn't get the setup like I like it on a single monitor.