Gtuner is a gtk/gnome based radio card tuner that has support for numerous different radio cards as well as the kernel drivers. It has a large feature list including: a scriptable GUI, themable panel applet, a 7 day alarm, an almost unlimited number of channels, gnome support, full GUI configuration and much more.
TerminatorX is a realtime audio synthesizer that allows you to "scratch" on digitally sampled audio data (*.wav, *.au, *.mp3, etc.) the way hiphop-DJs scratch on vinyl records. It features multiple turntables, realtime effects (built-in as well as LADSPA plugin effects), a sequencer, and an easy-to-use GTK+ GUI.
Cajun is a program that allows you to turn any computer into a massive audio jukebox for your car or home. It uses LCD displays/keypads, and supports infrared remote controls. Soundcard output is delivered to your (car or home) stereo for amplification. The software supports a playlist and shuffle mode.
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.
The GlobeCom Jukebox is a music jukebox with integrated CDDB-aware ripping and groupware functionality. It is completely configurable from the Web interface, seamlessly integrates ripping from CD to encoded MP3, and supports grouping of songs, peak adjustment, account management for access, streaming of jukebox or single song, themability, album handling, and online help.
gcombust is a CD burner GUI. It works as a GTK+ frontend for mkisofs, mkhybrid, cdrecord, and cdlabelgen. It has primitive support for controlling the directory (root) structure and size of an image without copying files/symlinking or writing 10 lines of arguments. It can also maximize disk usage by hinting at which directories/files to use.