Beets is a media library management system designed for obsessive-compulsive music geeks. It catalogs your collection, automatically improving its metadata as it goes using the MusicBrainz database. It also downloads cover art for albums it imports. Then it provides a bouquet of tools for manipulating and accessing your music. Beets also includes a music player that speaks the MPD protocol, so you can play music in your beets library using any MPD client.
gst123 is a GStreamer-based command line audio player in the style of mpg123 and ogg123. The advantage over these tools is that gst123 can play every file GStreamer can, so mixed music collections with FLAC, Ogg, and MP3 files are no problem. Newer versions of gst123 additionally provide support for playing video files, while the ability to use gst123 without X11 display has been preserved.
audiopreview is a command-line tool that plays previews of many audio file types (Ogg, MP3, etc.), video file types (AVI, MPEG, Real, etc.), and Internet streams. It can also be used as a regular command-line media file player (i.e. play the files entirely like yauap or mpc123 would).
Scenic is a free software suite for streaming audio, video, and MIDI between live events. It was created at the Society for Arts and Technology (SAT) to give artists a powerful tool for telepresence in live arts contexts, and new media installations. The streaming is done over RTP with the GStreamer multimedia framework. Users can also choose low-bandwidth or high-quality codecs, depending on what is available on their system. It offers up to as many audio channels as your audio device supports. It consists of a desktop application and several command-line utilities: scenic (a Desktop application to stream audio, video, and MIDI over RTP); milhouse (streams audio and video over RTP); midistream (streams MIDI notes and controls over RTP); dc-ctl (controls connected DC IEEE 1394 cameras); firereset (resets an IEEE 1394 bus to help in case of problems); and jack-info (prints information about running JACK servers).