I use one regularly. Its used primarily for the cross fire drill. (see SHAKER1 youtube link posted above for details) We bounce it into a wall from about 20' away while standing at an approx. angle of 45ish degrees.... This really creates a violent snap over for her drop ball.
I'll also use it when teaching the riseball grip and spin. If done correctly and spun up into the air a couple feet, when it falls and hits the ground it will bounce backwards...this proves her spin is correct. If it bounces off to the left or right, it'll prove her spin axis is wrong.