My new iTunes playlist sharing site, my2unz.com is up. Registration is by invitation only – contact me for an invitation.
I wrote one custom Drupal module that imports an iTunes playlist or library exported as XML and handles specialized nodes for playlists & tracks. The rest of it is mostly standard Drupal modules. I plan to add more functionality for searching playlists, searching tracks by member, and finding members based on their music.
Besides the iTunes specific functions, it also has more standard features like blogging, forums, and buddy lists.