Sponge Balls with Cards

Hey there,

I've got some sponge balls and I'm looking to use them with cards – essentially, a trick that combines both. The thing is, I'm not sure how to tie these two elements together. I'd love a good card magic routine blended with a visual sponge ball effect. I've thought about a trick where a spectator selects a card, it's lost in the deck, then I deal off the top seven cards and rub a sponge ball on each one. On the card I know is theirs, I make the ball vanish and claim that if it disappeared, it must be their card (and it is). But I'm not totally sold on it. Does anyone know a trick that uses both, or have any ideas?

Thanks!