National Study Group on Chronic Disorganization
"The National Study Group on Chronic Disorganization, an association of professional organizers, has established a household clutter assessment scale."
see the article at http://www.11alive.com/tech/tech_article.aspx?storyid=70921, a local Atlanta TV station (I don't know whether this is an exclusive, or they got it somewhere else). The article speculates that clutter is an evolutionary reaction, like overeating - saving up against scarcity. It suggests that these are modern phenomena because, for either obesity or clutter, large populations didn't have the necessary financial or food resources until recently.
The National Study Group's website is here: http://www.nsgcd.org/
No time to read further, just thought others might be interested.