Basically, the functionality is here, it just needs some refinement that I don't know how to tweak, I've written this small snippet that does exactly what I want, but doesn't scroll the whole page, it just scrolls the "window" size.
Can anyone take this and make it amazing? :)
$(document).mousemove(function(e){
percent = ((e.pageY) * 100) / $(this).height();
$('body,html').scrollTop( percent);
});
You may rather want to have a delta depending on how far the offset of mouse is with respect to the middle of the page: http://jsfiddle.net/BYUdS/2/. That way, you can keep scrolling down so that there is no scroll limit (what you have now).
Here's a version that performes smoother: http://jsfiddle.net/BYUdS/3/.
Something similar to this? http://jsfiddle.net/zcVL7/4/
I condensed the JS a little, but you had most of it: