CIOS Audio Core is the infrastructure and subsystem in Collective Intelligence Operation System. It is a cross platforms audio abstract interface, supports including Mac OS X, Linux, Android, iPhone OS and Windows 7.
TappedAudio is an audio library with an emphasis on the programming interface -- agnostic to the backend, written in highly-encapsulated C++ and using SWIG to present a unified API for C++, Python, Ruby, etc., regardless of the underlying audio platform.
Visecas is a graphical user interface (GTK+) for Ecasound (http://eca.cx/ecasound), a software package written by Kai Vehmanen (k@eca.cx) which is designed for multitrack audio processing.
A remotely administered jukebox server (written in Ruby) with the ability to output to a local device or to a stream. Administration is via XMLRPCfrom any number of sources but a web interface is included.