MusicBrainz Picard is a cross-platform application written in Python and is the
official MusicBrainz tagger.

Picard supports the majority of audio file formats, is capable of using audio
fingerprints (PUIDs), performing CD lookups and disc ID submissions, and it has
excellent Unicode support. Additionally, there are several plugins available
that extend Picard's features.

When tagging files, Picard uses an album-oriented approach.  This approach
allows it to utilize the MusicBrainz data as effectively as possible and
correctly tag your music.

WWW: http://musicbrainz.org/doc/MusicBrainz_Picard