I actually scan all my covers myself. I doubt that an P2P functionality for this would be usefull.

However I could imagine having a Cover-Art Browser that is connected to a search engine's picture search (Just like dBpoweramp and similar programmes do that)

I would recommend Musicbrainz picard for album art

It probably wouldn't be possible because of legal ramifications.

Maybe this has all ready been suggested before; but it wouldn't it be a smart idea to build a P2P application on top of mediamonkey for sharing cover-art between users? I can imagine that over time 90% of the users converge to one cover-picture for the combination: "Mack Morrison - Return of the Mack". Like this one*.

I like to take advantage of the the masses and save some time doing cover arts for individual tracks. Is this a crazy idea?

* http://www.google.com/search?hl=en&q=mark+morrison+return+of+the+mack&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&biw=1280&bih=923