Found a nice site/idea today when checking referrer logs:
http://www.itunesregistry.com/about.php
Basically, it allows you upload your iTunes XML library file, and it analyses it and compares it to others’ libraries. It is a great idea - much better than connecting to a database and sending individual queries/messages.
I’m not sure how it would go with matching up artists/albums where there are slight differences (spelling errors made by tools who can’t spell Adagio, or think it’s The Eagles, not just Eagles.)
Still, as a note to self, I’ll have to check it out. (And it should be cross-platform, since both versions of iTunes export an XML file).