How can I protect myself from power boats when I’m in a kayak?

I frequently kayak in waterways filled with everything form large ships to small boats and jet skis. I know the obvious: kayak whistle, lights at night, avoid busy channels when possible, etc. What I'm wondering is, what is the best way to take aggressive defensive measures when I'm about to be mowed down by a mullet headed jackass with a beer coozy in one hand, fishing pole in the other and his knee on the helm of a motor boat, who is aimed right at me but isn't looking or listening? How can I even the odds and create a visible, potentially destructive deterrent, so those idiots will avoid me?