Cross Fading Audio Found

[Doug Sutherland]

Not exactly what is meant by cross fading, but surprised nobody has
mentioned esound yet. It can fade multiple audio sources. And such.

http://www.tux.org/~ricdude/overview.html

This jack audio server thing looks very interesting too. I have
meaning to try this for some time. "It can connect a number of different
applications to an audio device, as well as allowing them to share audio
between themselves."

http://jackit.sourceforge.net/

More stuff
http://linux-sound.org/
http://www.vlug.org/linux/links/Audio-Video/