If you're not one to throw away a battery until you're absolutely sure it has nothing left to give you, then this Battery Eater by David Dear is for you (and probably looks like you, too). Just stick the AA battery you want all gone between Battery Eater's teeth, wait until its evil red LED eyes stop blinking, and then throw the battery away knowing it's completely dead.
That kind of emotional security will cost you $6.95. It's just a shame the Battery Eater doesn't really chew them up, as hazardously fun as that would have been. (Please dispose of batteries responsibly.)