We've never understood trackballs. Like the folks over at Dvice, we too remember being told that everyone would be be using them in a few years. That was 1995.
We tried our hand(s) at it too, with one about the size of a softball that was attached to an even bigger mouse--both of which were supposed to eliminate RSI forever. Years of physical therapy later, we're back to our old wireless Kensington. But we digress; clearly there are those still loyal to the trackball, for Genius has invented one that can even be used on the road by clipping it onto the laptop itself.