Can you be a little more specific about the scope of who "you" is? Startups, small businesses, freelancers, etc. I can answer this question, but I'm not sure I'd be polluting your data or not.
My guess is there is a lot of people with desktop/gaming machines which are powered off 20+ hours of the day. For startups/freelancers, I know I've got three or four machines which are powered off not doing anything other than depreciating.
The closest thing I have is an xbox 360 in a closet. I've got a 4 year old macbook pro in a drawer that I keep as a cold spare, a 3 year old macbook air that gets used about 4 hours a month, and a 2 month old macbook pro that is my bread-and-butter machine.
However, I do know people with basements full of hardware.