I'm thrilled with the kensington expert (trackball)... I don't like the small trackballs... but the ones with a ball the size of a pool ball are great once you get used to them. Rather then paddling a mouse around on a pad (moving your whole arm) you're flicking the ball around. What I really like about it is the larger ball has momentum... so I can sort of "throw" the pointer around the screen... again, by "flicking" the ball and keeps rolling... then for fine pointing I rest my fingers on it and have easy fine control.
The next thing I'm interested in (like this) is a big tablet... that will be my next move... I have little touchpads on my laptops (don't care for them too much)... but I will agree with the above and say I have no idea how anybody [happily] uses a regular mouse.