I really enjoy DIG Jazz from the ABC. The digital radio channel via the TV set-top box is great to have on in the background when working from home, or you can use the streaming versions when work pays for the bandwidth :)
One slightly annoying thing is you hear something good and have to go to the website to figure out what was just played. I de-compiled the flash application to see where it gets its information, and it turns out it is just a fairly boring XML file. Since I've been meaning to get to know PyGtk a bit better, I knocked up a simple applet that, when clicked on, shows you the current song playing.
Source code available here or I also made a Debian package.