Remember when RSS got a new icon some time ago? Within weeks and months, everybody agreed to use the new icons from Feed Icons.
I don’t know if this is old news, if anyone has suggested something like this before blah blah blah. But this is a very nice icon representing a podcast:

I think it’s brilliant. I found it at the Dumb Little Man blog, that showed up on a search I did on del.icio.us today. It’s made by Spoiltchild, but I couldn’t find any mention of it on their site.