A "google" search on the word superball brought up a number of interesting web sites:

• "That's the way the ball bounces" -- an essay, from the Exploratorium. It never would have occurred to me to freeze a baseball...

• "Ordinary and Super-ball Bounces" -- From PHYSNET, at Michigan State University. (I think Barger and Olsson's treatment of this is better.)

• Superballs web site -- lots of fun to read through.

• Rod Cross, "Measurement of the horizontal coefficient of restitution for a superball and a tennis ball", Am. J. Phys. 70, 482 (2002). Yes, a serious article (funded by the International Tennis Federation) on experiments on bouncing. Good references to theoretical studies are given here.