Easytag

View and edit tags for MP3, MP2, MP4/AAC, FLAC, Ogg Opus, Ogg Speex, Ogg Vorbis, MusePack, Monkey's Audio and WavPack files.

Look up albums in online databases, bulk edit tags, create playlists and rename a collection of files.

A simple and nice GTK+ interface makes tagging easier under GNU/Linux and Windows.