YaRET is a Perl script that automates the ripping, normalization, and encoding of CDs. It supports CDDB very well via the Perl Audio::CD module, and also can work with your favorite ripper/normalizer/encoder (e.g., cdparanoia, cdda2wav, normalize, etc.) It supports useful features like multiple concurrent encoders and an easy to use configuration file that lets you customize YaRET to your taste (such as file naming based on the CDDB information).
Zinf is an MP3/Vorbis/CD audio player with jukebox capabilities, formerly known as FreeAmp. It features both graphical (with themes) and text-based user interfaces, a download manager for automating MP3 downloads, and a powerful music browser/playlist manager. Other features include HTTP/RTP streaming playback with HTTP stream saving and title streaming, and a fast, clean-sounding Open Source decoding engine. It supports Win32/OSS sound systems, ALSA, and EsounD.
ZoltanPlayer is a music playing daemon. It accepts remote commands via its own mini HTTP server and can seamlessly use Audio or Data CDs. Audio CDs are played internally (optionally querying CDDB info servers) and digital songs in audio CDs are played via external players. It's not limited to CDs, as a hard disk directory can also be used.
abcde is a frontend to cdparanoia, wget, cd-discid, id3, and your favorite Ogg Vorbis (the default), MP3, FLAC, Ogg Speex, or MPP (Musepack) encoder. It grabs an entire CD and converts each track to the desired format, then comments or ID3-tags each file, all with one command. It supports multiple output in a single CD read, the creation of a single track from a CD, resume operation, CD concatenation, volume normalization, gapless encoding (with LAME), parallelization, SMP, proxies, customizable filename organization and munging, playlist generation, distributed encoding via distmp3, and more.
Apetag is command line tagging tool for multimedia files such as Monkey's Audio and Musepack that use the APE 2.0 standard. It also comes with a script, tagdir, that will tag all the tracks in an album by invoking apetag or other similar tools (e.g. metaflac) for each track. All that is needed is the album's freedb record.
auCDtect is a tool for analyzing the spectral characteristics of audio files and determining if they have been compressed with using codecs. It is useful for checking if a compact disc has been recorded using MP3 files or from an original source. Tests shows that it is more than 95% accurate.
audio_burn is a commandline audio cd burning application written in C. It uses libaudioburn (also written in C) for all of the real work, which in turn uses several other Free Software packages. It accepts WAV, Ogg, and MP3 input files, decodes them, and (optionally) normalizes them before writing them to CD.