xoscope is a digital oscilloscope using input from a sound card or
EsounD and/or a ProbeScope/osziFOX and will soon support Bitscope
hardware. Includes 8 signal displays, variable time scale, math,
memory, measurements, and file save/load.
MARF is a general cross-platform framework with a collection of algorithms for audio (voice, speech, and sound) and natural language text analysis and recognition along with sample applications (identification, NLP, etc.) of its use, implemented in Java.
MusicWatcher is a perl based non-realtime music analysis and visualization system with complete example implementations. One example renders a 3d music driven animation in povray.