Here's an interesting dimension to look at: prevalence of e-readers (and iPads etc) vs mass transit use. My train to work in the morning is stuffed with people

Here's an interesting dimension to look at: prevalence of e-readers (and iPads etc) vs mass transit use. My train to work in the morning is stuffed with people using various hand-held non-phone devices; I can't imagine they'd be as popular with car commuters :) Another (silly) one: e-readers vs holidays taken in hot places. Maybe people don't buy e-readers in California because they're already somewhere sunny, so they don't take beach holidays? ;)