OK, a few more fertile areas for exploration that I'm interested in, at least:
1. Physical Modelling Strangeness
Physical modelling synthesizer processes can be sources of incredibly bizarre timbres. Whether its the mis-shapen steel drum that morphs into a sitar-like blues harp or the distorted guitars that being to overblow like trombones, there are seemingly infinite new sound sources in the mis-use of physical models.
2. Physical Modelled Noise Production
In Perry Cook's recent book Real Sound Synthesis for Interactive Applications, which by the way includes an audio CD and tons of C++ source code, he introduces plenty of models for producing natural sounds such as glass breaking, walking on snow, other chaotic and complex sounds we live with. Using these models in music should provide a rich source of very complex percussion sounds and noise textures.
Book Info:
Author: Perry Cook
Title: Real Sound Synthesis for Interactive Applications
Publisher: AK Peters Ltd.
Year: 2002 ISBN: 1-56881-168-3
Price: $39 250 pages