There are plenty of music and media players that will handle streaming Internet radio, or you can use a web browser, but radio is meant to be heard, not seen. That's why a program like Radio Tray is such a good idea. As you have probably already guessed from the name this is a radio program that sits in the system tray.
There is no GUI apart from the configuration window that pops up when you right-click on the tray icon, where you can add and edit the list of stations. This is the one area that really could do with some improvement, I don't know how many streaming radio stations there are, but it's a big number, and Radio Tray comes preconfigured with the sum total of four. Adding extra stations is as simple as pasting the URL into a box, but it would have been nice to have a few more default choices.
Radio Tray uses the GStreamer framework to play the audio and it currently supports Shoutcast/Icecast playlists and m3u playlists along with ASX, WAX and WVX format playlists. RealMedia is also supported, leaving the most noticeable omission of the BBC's iPlayer format, but the BBC also broadcast in other formats, so that should not be a problem. Overall, this is a superb little tool for unobtrusively playing online radio, let down only by its sparse default station list.