Tone is a Google Chrome extension to transfer data over audio within a short distance. Tone was designed by the Google Research team. Not surprisingly, it started as a fun project to share data.
The idea is to broadcast data like documents quickly with people around you vi a broadcast mechanism behaving like the human voice. The reliability is boosted because nearly all laptop microphones and video conferencin devices are voice-optimized. A minimal DTMF-based audible codec is used as the audio format. It works at low volumes as well as over Hangouts. Because the technology is audio based, all the devices will not receive the same quality of transmission. But resending is easy and increasing the volume fixes the problems in most cases.
Coming back to Tone, this is a working application of the same technology for the Google Chrome users. Currently it can transfer URL of an open tab and open the same URL in the browsers of the audience. Using it is quite simple: open the URL in a tab, make sure your audio is on and press the Tone button. Your machine will emit a short sequence of beeps. Nearby computers receive a clickable notification. When a receiver clicks on it, the browser opens the same URL.
Chrome Extension page: Tone