Used to listen to the King Biscuit Flower Hour every week. Sigh. Many FM stations in those days had a regularly scheduled time when they'd broadcast a recorded concert or live album (hint hint, wink wink). ;-) For Doors fans, Robbie Krieger has put together a CD collection called "Boot Yer Butt" with the best of the bootlegs. It was these type of recordings of live concerts that use to be broadcast, unofficially, of course. see:
http://www.thedoors.com/bmr/boot.html