SlideShare Zeitgeist, a look back at 2011 presentation trends based on activity of the SlideShare community.
I found it especially interesting (though not surprising) that Keynote accounted for a much higher ratio of most liked presentations (despite accounting for a smaller percentage of presentation) and the relative number of average slides used in different countries (I can attest to the high number of slides in Japan and China!)
Source: slideshare.net