Music has always caught the public's imagination. From dreams of a giant "jukebox in the sky" over the Information Superhighway to the debate about Napster, music has always been the "killer app" used to describe new technologies. Of course, these dreams have never quite come about as planned. Instead of a smart machine seeking out music tuned to my tastes, I still have only a small number of choices on my radio dial. And ever since Napster started filtering, sharing music on the Internet has become increasingly difficult. One thing that underlies these ideas is their dependency on metadata, or data about data. Metadata provides information about artists, song titles, and so on. All that information is attached to the music, but isn't part of it. The music world suffers from a lack of standardization in terms of metadata formats, as well as a paucity of public metadata. The MusicBrainz project hopes to change this situation. It's a large database of music metadata, and even though it's only in beta testing right now, it already contains over 300,000 tracks. MusicBrainz information is all user-contributed, providing what some have termed the "cornucopia of the commons." Unlike many situations, where each user decreases the value of the shared space (the so-called "tragedy of the commons"), the easy duplication of electronic information creates a situation where each user makes the system more valuable.