I thought I'd start a thread on this modulation source since I've started using it with my latest round of sound design experiments with Saurus.
It's pretty much a built-in envelope follower. Final output from the synth can be used to modulate any source. It's cool because it's a bit predictable but with a chaos around the edges :^).
Below is a screen shot of a patch I'm working on. I'm using VoiceOutput to create very warm yet unstable patch using it to modulate OSC2 Tune, and LFO1 speed which control OSC mix.