I don't know why I was thinking about this the other day - but it came into my head that I really like "split buttons" and think they are very usable, for the right situations. I'd better explain.
"Split buttons" are buttons that also have a drop-down menu. Pressing the button should carry out an action*; alternatively, clicking on arrow to the right of the "split" should display different but similar actions that can be performed by clicking on the menu item. I don't know if "split buttons" have a better name or are even accepted controls, but they've been used...