A few years ago (I guess it was 2006?) we had an online radio, managed by Christopher Duncan, made up completely of composers using Garritan products. Unfortunately I think it cost a bit too much time and money to maintain ('twas true streaming after all ) so it didn't last.
Anyway, I found this fun website: Radionomy. It allows anyone to create a free online radio, with true streaming, like a real online station would be, and the content can be whatever you wish. They say it will be ad supported, so they'll put automatic ads in your stream (between content, I suppose), but they just opened their doors, so I haven't heard them in place yet. If your radio station becomes very popular, they say they'll even share a bit of the revenue with you (not sure that's very probable though ).
It was easy to create a station. I created Wizard Walk, which basically just streams a bunch of my music in random order. Hardly exciting. And there's only so many hours one could listen before re-hearing stuff, so it'd be great to have more content.
If there's any interest, we could probably create another GPO station (or a few, for different styles).....
Of course, we can't be sure how long Radionomy.com will last, or at least stay free, but at least it's free for now.