mpgfe is an ncurses front-end to mpg123 with mouse support via GPM, advanced playlist editing features (load/save/add playlists in m3u format, order/shuffle a playlist, move/add/delete playlist entries), and resizing support. An interesting feature is the ability to display the lyrics of the song that is playing (provided that you added the name of the lyrics file after the song file. Song information is displayed while playing, in a customizable format. Volume control is available (both channels at a time) and also movement. You can display the length of every song and total playing time. The super user may run the player with real-time priority (playing will not be interrupted by disk access).
Mp3tag is an Objective-Caml library for reading and writing ID3v1 and v2 tags in MP3 files. It includes mp3tag tools, which can be used to modify tags in MP3 files or rename files according to their tags, and a cddbtag tool that modifies tags by using a CDDB server to retrieve information about the track.