> As for iTunes, given that you really "need" those metadata (which is usually superfluous stuff, like people spending eons tagging their music collection and less time actually enjoying the music), the solution is quite simple for a hacker: write, or get (there are some on the internet) an Applescript that writes those metadata to the mp3 tags.

Honest question: which metadata does iTunes stores on proprietart files? Album covers and ID3 stuff go into the files, playlist can be exported to m3u...

I have an external drive with music that I lug around and I use the same files seamlessly between iTunes and foobar2000 at work.