Apollo is a user-friendly X11 front-end for mpg123 using Qt for its GUI. It has a compact, playlist oriented user interface.
Kmpg is a Mp3 player for KDE. It has playlist support, can seek in mp3s, has a build in mixer for mp3 streams, a build in volume/balance control, ipc mechanism for multiple instances, a nice spectrum analyser, esd and id3-tag support.
KPlayer is a KDE media player based on mplayer. It provides video, audio, and subtitle playback from files, URLs, DVDs, VCDs, and audio CDs, and features basic player controls and a status display.
Knight Rider MP3 Player: a free full featured car mp3 player that uses the Xaudio mp3 server and the Festival text-to-speech system to create a interactive car mp3 player without an lcd screen.
lnkMusic is a powerful and easy-to-use interface for MPD (Music Player Daemon). It features playlist sorting and a system tray item that lets you control MPD without having to open the main window. The tag browser is similar to the one in amarok with an integrated search engine.
Pyamp is a recursive acronym for Pyamp: yet another music player that supports MP3/OGG/WAV, playlist editor, tray docking, incremental search, drag-and-drop, konqueror integration and UTF-8.
The Sajber Jukebox is a mpeg layer 3 player with a graphical user interface. It's based on Woo-jae Jung's splay for the audio and QT's graphical library for the interface.
ZZplayer is a MPEG player for the KDE environment. Currently Mpeg I video, MP3 and VCD are supported.