Quod Libet is a GTK+-based audio player written in Python. It's designed
around the idea that you know better than we do how to organize your
music. It lets you make playlists based on regular expressions (don't
worry, regular searches work too). It lets you display and edit any tags
you want in the file. And it lets you do this for all the file formats
it supports -- Ogg Vorbis, FLAC, MP3, Musepack, and MOD.

Ex Falso is a program that uses the same tag editing backend as Quod Libet,
but isn't connected to an audio player. If you're perfectly happy with
your favorite player and just want something that can handle tagging,
Ex Falso is for you.