Could the explosion key have a customizable setting? F1 on an Internet browser keeps bringing up help. F2 would be great, though, since that only opens the Renaming capability in file browsers.
Support for multiple monitors would be great. It'd be so cool to explode letters onto other monitors!
I would personally love if there was an option for the keys to very slowly descend off-screen at the bottom, as if it's like quicksand down there. That way, if you wait long enough, the characters would gradually remove themselves. I would keep this program going perpetually then; that'd be pretty hilarious.