How to make a presentation work

Anyone who's anyone working in a communications environment has had, at some point, to have given a PowerPoint presentation.  And yet, most people are truly rubbish at using a wonderful communications tool.  By far the best person I've ever seen do it well is Professor Lawrence Lessig who, apart from being one of the cleverest academics in the world, is also a phenomenal communicator.  His "style" of presentations is almost jaw-dropping the first time people see it - so here's one of his earlier versions.