Recently I had to do a presentation for English class where we chose a technical innovation and explained how it could be abused if it fell into the wrong hands. After about five minutes online I found this pretty cool innovation called the Audio Spotlight System.
The Audio Spotlight System is a cool new speaker that allows you to have directed sound which is almost tight as a beam of light.
This image from their website shows the tight range that their speakers offer. Perfect for weirdos like me who hate wearing headphones but also hate having other people listen to their music.