On the topic of learning to use a trackball...

I was forced to learn how to use one at work because it was all my boss used and I was stationed at her desk for the first two weeks I was there. After a good week of using it frequently I caught the hang on it and then found out I absolutely LOVED it in gaming!!

It's so easy to do 720 turns on a simple jump while running, the turn response time is excellent. I imagine first person shooters love these mice.

I would recommend it in a heartbeat to a multiboxer. I currently have (2) thumb driven Logitech Trackball mice sitting on (1) mousepad on my desk. The beauty of it is never having to move the actual mouse around, just your thumb.

I use a wireless one for my work laptop and absolutely LOVE watching first time users sit down and curse as they use two fingers on the ball to get the pointer to go where they want it too ROFL!!