The first utility i bought years ago on windows 3 was a mouse utility called squeaky mouse. It had a cute icon, and a lot of useful features from positioning the mouse over the active button, autoclick, help for scrolling lists (jumping by clicking a character, which didnt use to exist), smart scrolling modes, and some keyboard shortcut help (plus a trashcan and the list goes on).
Several of these features are still needed today - and more of them on vista than XP... the irony is not lost on me.
So yes, I would be curious to know of tools that really improve scrolling, listing etc. although my tendency is to do more and more with the keyboard, and not have to move my hand to the mouse (a desktop keyboard with a little "nipple" or mini joystick or trackball spot in the middle, maybe where the thumbs reast would be cool, for now i am stuck with using keyboard extending tools)