somaplayer is music player for MP3, Ogg, wav, audio CDs, MP3 streams, and Ogg streams. It is able to use the appropriate sound drivers or demons or to stream directly to an Icecast server (Icecast2 or SHOUTcast) or to encode in MP3 and Ogg Vorbis. It also acts as a sound daemon that is able to accept connections from other somaplayers or any other sound player (xmms, mpg123, and others) thanks to a special wrapper.
GNUdap is a project to build a userspace driver to interface Linux with proprietary-protocol USB MP3 players and mass storage devices. Currently, GNUdap supports only the "Perstel,Inc. CHIC MP10". GNUdap is also an experiment to test the advantages of a strongly-typed programming language and of the functional programming paradigm in hardware development. GNUdap currently supports all features supported by the official program provided with the Chic, and has some additional features, like being able to transfer MP3s directly to the PC.
cmus is a small, fast, and powerful console music player for Linux and *BSD. It supports almost all common file formats, SHOUTcast/Icecast streaming, and multiple output plugins. cmus features multiple media library views, a playqueue, a directory browser, powerful filters, and vi-style search and keybindings. It also features gapless playback, ReplayGain, Unicode support, and customizable color schemes.
Yet Another Time Machine is a command line Ogg Vorbis and MPEG audio player with the ability to control the tempo of playback without changing the pitch. Primary usage would be to listen (for example) to audio books at 150% tempo. This is still understandable and saves time, hence the name of the program.