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