Wolfgang's Vault has become my default radio station at work. When I don't know what I want to listen to, I just click around in their list of artists and try something. Live Music Archive, the same, but it's interface is much more tedious and you don't always know if every show will stream and I'm basically a very, very lazy man. A lazy sod.
So I've stuck a widget at the bottom of the sidebar for an awesome Roky Erickson tune. Click on the link and hear the whole show for free. I think you have to register, but that's free, too. I'll change the tunes every once in a while, but it'll be some time before I'm tired of hearing Roky.