Easy Convolution with Sound Hack.
SoundHack, a freeware program by Tom Erbe, has some terrific and unique functionality for manipulating sound - including convolution.
Convolution, a type of analysis-based sound file manipulation often used for reverb, can be used to generate some extremely interesting sounds by “cross-breeding” two source sound files. This can be done programatically with a number of music programming languages like CSound and Max/MSP, but SoundHack makes it quite easy (and free).

An Example:
Here I’ve taken an alto flute sample:
And convolved it with a female voice sample (courtesy of the freesound project and digifish music):
To produce:
This technique of convolution was used heavily - actually for every sound in the piece - for the piece Sunbeams Through Stained Glass.
