www.mymbn.com/swing/ << go to that on your blackberry.
Note: This is NOT a music playing application, it is a directory of streaming music stations that are accessed by a voice call. You can search the directory and select your station; then your cellphone will MAKE A REGULAR CALL (Yes, this means you do use voice minutes) and you will hear the audio stream live.
It's not the most pratical way of doing things, but it does work. I guess it's most usefull at night or weekends when you (most likely) have unlimited minutes anyway. - I got myself an FM transmitter and adapter for the smaller audio plug; it's nice to have something else to listen to in the car on the weekends; even if it's low quality. Still good for news and talk though.
Once again: Listening to a stream will use voice minutes.