"a freeware standalone sound-mangling application for Mac OS X built with Max/MSP 5. It was designed with both live use and studio work in mind. Simply put, Sapling is a program for remixing up to four audio files, but can offer some very interesting and unexpected results by offering several realtime randomization features."
It looks like it has some nice features. The website has some audio examples of the kinds of things that it can do.
The audio output can be saved to disk for further mangling / experimentation.