How can I listen to Internet stream though ATV2?

I’m trying to listen to the audio stream from but I haven’t found a way to do this yet.  There doesn’t seem to be a way to add it to the list of radio stations supported by ATV2.   I tried usiing the web browser in CouchSurfer but don’t get any audio when I click on the link to get the stream.   I even tried getting it to play by linking to iTunes in my MacBook, but radio streams don’t show up like links for music, video, and pictures.   Does anyone know if it’s possible to do this?  Thanks.

atv can stream custom urls via itunes. but i’d like a solution without any computer running in background. is there a way to do this?

Last FM will run with the TV off through ATV2 if connected to a sound system. Closet thing I can think of.Ipod Ipad works the same way.