When using a scroll wheel on your mouse, trackball, or tablet, there are some modifiers that can be very helpful when navigating in Pro Tools. (especially the edit window)
Shift – Scroll: Horzizontal Scroll
Option – Scroll : Zooms horizontally depending on which way you scroll.
Option – Shift – Scroll : Zooms your waveform size in the edit window.
Command – Shift – Scroll: A finer horizontal scroll.
Command – Scroll: A finer vertical scroll.


Also, if you have an older trackball without a scroll wheel you can set up a button combo (I use the bottom 2) to change the mouse to scrolling, and all of these key commands will apply.
[...] This post was mentioned on Twitter by Allen Wagner, PTDudes.com and PTDudes.com. Allen Wagner said: RT @ptdudes: Use your scroll wheel for good, not evil. http://tinyurl.com/ptscroll [...]