1. I'm always interested in lo-fi analog style delays, similar to an old Deluxe Memory Man (with modulation available for the repeats, of course).
2. Can you create a good approximation of a Leslie/Rotating speaker using existing Eclipse algos?
3. Pitch-shift + Tremolo would be great (reference U2's, "Lemon")
4. New, improved whammy?
5. Univibe
