Two feedbacking pitchshifters can make endless noise:

Stefan Blixt used this as the basis for a rhythm patch:

sbt_shiftbackbeat.pch2

Read more in Rob Hordjk's basic workshop on Clavia's website.

One cute patch involves adding a stereo reverb before you send the signal into the VCF. It is also fun to have a reverb feed sent into a seperate envelope.

Stereo reverb is perfect for adding movement when you stepfilter a sequence. One might even use an envelope section before the stepfilter section and then play the envelope settings too. So many possibilities.
You see.. if you use a mono signal from the VCO´s.. then you run it thru the usual path.. with VCF and envelope.. then you add some some stereo reverb to the mono signal.. then you set up two identical channels with a VCF and envelope section.. the VCFs get the same values from the sequencer.. but because you have added the stereo reverb.. the sound will move.. you then tweak the final envelope section in order to get max effect.. and the sequencer can also run tonal sequence too.. or you can play the sounds by hand or whatever..

Another cute patch is splitting the signal inside the patch and have the reverb handled by a separate enveloping section which for instance can have clatter and clutter from the reverb hit in slightly offset.. so like when you are in the late decay step for the clean synth signal you have a starting reverb peak hitting in .. and you can round this off during the sustain of the clean signal so the sound kinda crossfades. If you do this with a stereo signal you can have like a whole landscape of wild sounds crossfade with the clean signal. Hmm.. i have often done similar stuff with ping pong echo which hits in and then fades out.. stereo.. If you do this on a modular synth .. then you can play several of the parameters in a way that is pretty exciting.

I have even used ducking gates to pick out a control signal from ping echoes and used the amplitude of the ping pong stereo echoes for running the volume of the reverb feed up and down. Pretty amusing to have ping pong stereo reverb instead of ping pong echo.. 
I guess picking up some kind of control signal from somewhere and using this for varying the reverb parameters should do the job of a stereo reverb.. hmm.. is it possible to set up l "walking notch" filters? That is pretty effective if applied to broadband noisy stereo sounds.
I forgot to add that limiters set up to beef up the volume dips in the stepfiltered signal.. and also for controlling the peaks.. in some sof those patches I mentioned in that other post.. is a must..

elektro80 on electro-music.com