I once read an academic paper where they used scroll bars with 2 dimentions of 
action. 

Up & down motion worked as expected. 
Simultaneous left & right motion bumped the menu up or down a level of detail 
(all submenus, then all sub-submenus, etc.) to create a zoom effect.

Obviously, keyboard is better when touch typing.

Jeff Raskin summarizes the "habituation" GUI's should encourage in his 
book "The Humane Interface". 
http://humane.sourceforge.net/humane_interface/summary_of_thi.html . He also 
summarizes best navigation techniques based on cognitive psychology. He 
promotes not modifying current menus based on user needs/experience but create 
new menus specific to user needs per current task/environment. Hot key to the 
new menus and treat them like content.

Cheers,
Darius