i was thinking about something like this too. i have a number of press downloads with PDF press kits. Some hard copy CDs also have PDF booklets available on the "enhanced" portion of the CD.

In fact i think a general "file attachments" feature would be useful. Some hard copy CDs have extra songs in MP3 format hidden in the enhanced portion of the CD, for instance. All that would be necessary is a field for description and a link to the location.

It's not at the top of my OCD wishlist, but i would welcome a file attachments feature.