X MultiMedia System (xmms, but formerly known as x11amp) is a sound player written from scratch. Since it uses the WinAmp GUI, it can use WinAmp skins. It can play mp3s, mods, s3ms, and other formats. It now has support for input, output, general, and visualization plugins.
xmms-1.2.7: description + notes
The Xmms Homepage has on-line documentation and lists of skins, plugins, icons, etc.
NOTE: OpenGL-based visualization plugins (like the OpenGL Spectrum Analyzer, and geekosphere) can be started manually, but will crash if started automatically when xmms is launched. Don't leave them running when you shutdown.
To auto-install this package, go back and click on the respective install icon.