MuSE is an application for the mixing, encoding, and network streaming of
sound. MuSE can simultaneously mix up to 6 encoded audio bitstreams (from
files or network) plus a sound card input signal. The resulting stream can
be played locally on the sound card and/or encoded as an mp3 bitstream sent
to a broadcast server. MuSE offers an intuitive interface to be operated
realtime and can run in "slick" mode from command line.

WWW: http://muse.dyne.org/