Best sponge ball routine I've seen lately is Greg Wilson's.
For one thing, it doesn't use sponge balls. You start with two cocktail napkins and roll them up into balls. There is nothing else in your hands.
The first sequence is the same as the final sequence in John Carney's excellent routine. But then Greg adds a third ball in an extremely natural and deceptive way.
The third ball is used to cancel the method from the first sequence, and vanishes to the same place it was stolen from.
I'm pretty sure it's on Greg's latest two-volume video set, but I learned it at a lecture so I don't even know the name. It's a hell of a routine, all the better because all you need to do is secretly ball up a cocktail napkin and hide it and you're ready to go anywhere -- even if you left your sponges at home.