Now that we're on the topic...
How about this new feature: Filter feedback. The signal coming out right after the filter and the amp-envelope would be fed back to the filter input. You could control the amount of feedback with some parameter. This way you could create some really ripping kick-ass sounds
Another missing feature that I can come up with is noise mode for oscillators. This way you could ringmodulate oscillator with noise. This trick can create really nice tones.
Some very different sounding filter mode would also be nice to have. The current modes are very good, but I think that there's never enough of different filters