Mp3blaster is an interactive text-based program that plays several audio file types (MP3, Ogg Vorbis, wav, and sid). It is one of the few audio players for the text console that allows full interactive control during playback. One of its key features is the ability to compose a very flexible playlist (while playing!). It plays most MP3 formats and has full mixer support built in.
Paloma is a program to manage an SQL database of digital music files, and facilitate their retrieval and playback in interesting ways. It works with music files of any form -- MP3, Ogg Vorbis, MIDI... whatever you've got a player for. Paloma makes it easy to rip your entire CD collection and store it on your hard disk (or a collection of CD-Rs) for instant random access; playlists can then be generated using arbitrary SQL commands.
Parallel Bladeenc is a true parallel version of the Bladeenc MP3 encoder; it distributes work across CPUs to speed up MP3 encoding. It uses the Message Passing Interface (MPI) for parallelization across SMPs and/or multiple machines. Hence, if you have a 4-way SMP, you can encode your MP3s about 4 times as fast as the regular Bladeenc; if you have two 4-way SMPs, you can encode about 8 times as fast.
SoX is the Swiss Army knife of sound processing tools: it can convert sound files between many different file formats and audio devices, and can apply many sound effects and transformations, as well as doing basic analysis and providing input to more capable analysis and plotting tools.