Virtual headphones:

A team, led by Ivan Tashev, a software architect at Microsoft, recently began work on an algorithm that, in theory, will be able to direct sound from a set of speakers -- ideally embedded in a computer monitor--into a person's ears, effectively creating virtual headphones; just a few inches outside the focal point of the sound waves, the volume dramatically fades away. Crucially, says Tashev, his algorithm could be used by a wide range of inexpensive speakers that could be put into computer monitors.

The goal, he says, is to "target focused sound so that a person can walk around an office and hear" while on a video- or computer-aided audio conference call. Information about a person's location could be collected by hardware peripherals and fed back into the speaker software, allowing the virtual headphones to move with the user in real time.