Audacious is a very handy lightweight audio player for the Linux desktop.
Its powerful engine provides excellent playback quality of many formats and codecs.
The playlist manager works just fine and has some good features. Audacious does not include a media library.
The looks can easily be modified using Winamp Classic skins.
Many plugins offer extra functions like an Alarm, Crossfading, Last.fm-Scrobbling, audio effects a.m.m.
Some basic visualizers are included.