MP3DB2 is a collection of bash scripts for keeping track of large MP3 collections. It will retrieve song information from the filenames and ID3 tags of a directory or CD of MP3s and store them in a local database. It then allows you to search any of the fields, generate a master listing of all your complete albums, see the size of your entire collection, and more.
MMLi is a simple Music Macro Language interpreter written in ISO C99. The Music Macro Language originated in 8-bit BASIC implementations (as part of the “PLAY” command), and can still be found in modern BASICs (like QB64) and in system software (like FreeBSD's spkr.c driver.) This interpreter features an example "mmlitest" program which can be used to translate MML sequences into beep(1) commandline arguments.
UModPlayer is a multiplatform console module playing software for UNIX systems (such as Linux or NetBSD). It provides full sound option customizing, playlist support (with the ability to move, edit, import, and save lists), a WAV and AIFF writer, a file browser, a message viewer, an instruments viewer, and much more. It uses LibModPlug and LibAo.