Picturephoning found an interesting story about NTT DoCoMo developing acoustic OFDM (Orthogonal frequency division multiplexing) technology, which can then embed URL's and text data into audio.
"Consumers' mobile phones "listen" to the music/audio and extract the embedded URLs/data. About 100 characters can be transmitted in a second. (To deploy this technology, broadcast stations will need to install a dedicated encoder. Mobile phones need to be enhanced with a decoder mechanism as well.)
"DoCoMo thinks this technology can also be used at shopping malls and supermarkets. Then, the sound from in-store speakers would probably be delivering information about specials, ads, discount coupons, etc