Like tautech said I also use one Trackman Trackball from Logitech the T-18RA, and it's great, you can put it anywhere.
I've just finish to put my new bench together [will take pictures tomorrow], it's 3 meters long by 1 meter deep, with an upper shelf 47cm above [for the monitor] 3 meters long by 50cm deep.
Now to buy some ESD rubber mat, test cables holders, and start to putting some gear on top of it.