I can’t believe that I used to actually move my entire hand to move my mouse. It is much more comfortable to only move a finger or two, especially for a lazy person like myself. If you have never used a trackball before, I recommend trying it out.
I first used a trackball when it was the only available option on a very cluttered desk. Since you do not move a trackball you can use it on any kind of surface and save space. Also, if you are stuck with a very high or low surface, moving a conventional mouse can hurt after a while. When I first started, it was difficult and time consuming but after a while I forgot that I was even using a trackball and it became second nature to me. Now after using a trackball mouse frequently for half a year, I feel awkward dragging plastic on a desk with those lowly, inefficient, and antiquated pointing devices.
Right now I am using a Logitech Trackball. There is very little resistance on the ball; it feels like my fingers are floating. It has four buttons and I use the upper left click as a middle click. This is great for closing tabs in Firefox and scrolling, although I do miss my old scroll wheel. It is fun to take the ball out and play with it. My Lego alligator definitely enjoys it and you can even play pool with it if you really want to.