DoCoMo developed a technology that can be used to embed URLs and text data in broadcast audio. Consumers' mobile phones "listen" to the music/audio and extract the embedded URLs/data. About 100 characters can be transmitted in a second. The technology is called orthogonal frequency-division multiplexing (OFDM) (via RFID in Japan).
On the same note, it appears that Nokia began shipping its new phones with built-in reader for 2D barcodes.
