Yeah, I know they can do that. I've even had a mild version of that before, I was in a friends car, he had a subwoofer, and there was this "song" that was pretty much just a single pitch that was way down low. He turned the stereo way up and I remember having this slightly dizzy feeling... I turned the volume down and it went away.
As for killing somebody with a sound, I bet they'll be able to do it someday, but probably not in the near future. Even if they do, it would be a really dangerous thing to use as a weapon, because sound travels out from a source in all directions... So you're also hitting yourself with it...