What kind of mind does Jason Kravits have, anyway? His popular improv show, Off the Top! readily reveals the answer to this burning question. Kravits has a quick mind"on steroids. It's probably some sort of super power. Improv specialists are noted for their ability to conjure up instant "reality," but the ease and facility with which Kravits does it is a wonder to behold. And he's funny"really, really funny. At t…