Sony has come up with an answer for those infuriating moments when you hear a song on the radio that you like, but wait in vain for the DJ to name the band.

The eMarker is a tiny electronic device wrapped in an orange plastic oval and designed to hang from a keyring.

When its owner hears a mystery tune, he or she clicks a button and the eMarker notes the time, just like a stop watch. When the device is plugged into a PC, it launches the eMarker website, and all that remains to do is to key in the name of the radio station, and up comes the title of the tune.

The website also offers information about the song, audio clips, and samples of other songs from the album. There are also links to retailers to buy the album, with the site receiving a commission for every sale. Up to 10 songs from a variety of stations can be stored by the eMarker to be looked up at leisure.

It is the first product of a new Sony subsidiary, eMarker.com, whose purpose is to create products that link the old media with the new. Future versions will work with music video channels, and advertisements.

However, British music fans will have to wait to get their hands on the new toy. It is at present only available in the US (at $19.99), where the eMarker website obtains playlist information from Broadcast Data Systems, the company that supplies radio airplay data to Billboard magazine for its charts.

No decision has been taken on offering it in Britain.