Whatitunes prints in Dashboard what is playing in iTunes, and if you are listening to a radio, it will also print what is playing, taking the info on the radio website.

If you are working on something, listening the radio you like, and they play a song you love, you can click on the title name, it will be saved in a file in ~/Music, thus you can keep going on what you were doing and see later what you have saved and search more info or buy it... For now, Whatitunes supports only two French radio (nova & FIP), but more will come, on demand.