Mark as read/listened to for MP3 links

It would be great to have the ability to see a mark as read, but in this case, mark as listened to with mp3s I've already listened to on my favorite blogs. This would be such a great feature because one would be able to sort quickly what's new, old, and already listened to.

I'm sure there's got to be an easy implementation for this: all that needs to be done is check the browser history and the click through.