Script Summary: Use the scrollbar from anywhere on the page, or grab-n-drag.
Copyright: 2009, 2010, James Campos
License: cc-by-3.0; http://creativecommons.org/licenses/by/3.0/
Activate with the middle mouse button. In the source, change grabndrag to true for grab-n-drag style scrolling.
Sort of a clone of Marc Boullet's Scrollbar Anywhere extension.
Sometimes (not often!) the screen flickers while scrolling. I'm not entirely sure why.
Chrome: if content expands and creates a new margin, this script is dead in that margin. Not sure why.