There is one that I would like to know more about with regards to if it ever got released in some way shape or form - the one I am thinking of was on tommorows world as well as the gadget show
Using laser compression or some weird technology to basically supress sound waves so the only person / people who could hear the audio were people or persons directly under the laser
would be handy to listen to music in bed without interfering anyone else :D
Woody Norris invents amazing things | Video on TED.com
That guy patented directional sound in some form and tested it in supermarkets in the states for advertising at checkouts.