Number three is interesting, especially if we consider what Canonical have done recently with Unity and moved scrollbars <i>outside</i> the window[1], freeing-up the screen real-estate that they permanently occupy.<p>[1] <a href="http://design.canonical.com/2011/03/introducing-overlay-scrollbars-in-unity/" rel="nofollow">http://design.canonical.com/2011/03/introducing-overlay-scro...</a>
Most of these have been pretty well known or obvious, which is why those that do them have little excuse. But I disagree strongly that #1 is a problem. Some things, like the header in his example, usually should be full width. While others, especially columns of text should be of a fixed maximum width to improve readability. Who cares about blank bars to the sides of the screen? Or at least, who cares as much as they do about struggling to read too wide columns of text?
I'm curious what others think about #3 (The vertical scrollbar). Traditionally it's considered messing with the defaults of the browser, and wasting precious screen space; but I hear from more and more (graphical) designers that they'd like me to stop the page from jumping by doing exactly this.