I don't know how many online radios make use of a txt file for showing current played track on their sites, but one of those is HardRadio.com.
They don't show the played track from the playlist file, insted the show the artist and track in a flash on their site.
The info for the track appears in a text-file on their server.
The url is: http://axl.hardradio.com/playnow.txt
I don't think it would be too hard to implement support for something like this.