Here's my reasoning / hopes behind my original post (and wow, I've enjoyed all the interesting and useful commentary!)
I am a subscriber to Napster Premium, and with this service I can download as many tracks as I want and integrate them into my personal library, but I can't burn any tracks without first paying 99 cents.
The Napster WMAs look the same as my other music files, and so it'd be really helpful for me, when making mix CDs for friends, to have a column (NOT a view) that indicates whether a track is from Napster or not. This way, for instance, on my Christmas Songs playlist, I can quickly assess how many tunes are Napster tracks and, consequently, how much moolah I'd have to shell out if I wanted to burn the playlist as is.
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A similar issue could be made with my "Mood" request. In any given playlist, I might want to see, at a glance, how many of the tunes are "upbeat" and so on.
Though I admit, at least from a personal standpoint, the Napster example is more compelling.