KMP was a simpler GUI player for the Music Player Daemon made using the Qt toolkit. It was a good choice for controlling MPD around 2005. It's homepage dissipated ages ago and with that it seized to exist.
It's a shame because it was a nice piece of software.
Stand-alone music players:
Music Player Daemon clients:
mpd is a database-oriented music player daemon which can be controlled by numerous front-end programs.