It's pretty clear that the single-gaussian(ish) function is insufficient to cover the breadth of different distributions people would like to enter in numerical predictions.  It is, however, quite nontrivial to work out exactly what there *should* be.  

A current proposal on the table is that as a "power" (i.e. that you get at a certain level or buy with tachyons) you can get a second gaussian (or perhaps more), and that as another power, you can get a piecewise-linear function.

Subtleties:

* For each additional function, there is another parameter that is its overall normalization

* As for the current gaussian, we also need to retain a way to express how much of the PDF lies off the edges of the range.

* There has to be a workable UI.

Thoughts on the sort of distributions you have *wanted* to be able to express but have not been able to?  Would the above suffice to cover your needs or should we contemplate something different?