dual monitors for programming

I know the main userbase for dual monitors are for graphics artists, but Im wondering how much of the programmer community uses dual monitors? I imagine that large hi-res wide-screens have solved a lot of problems with screen real estate for programmers, but Im curious what percentage of programmers use dual monitors in their work.

I have 4 monitors, though I rarely even make full use of 2 of them at any given time.

Feels like a waste of money and electricity, man.