Have the ability to insert rows or columns with custom calculations based on values presented in the table; so based on the table you have presented in the cross table, have an edit feature to allow for insert rows with calculations that can be applied to existing data in the cross tables. Think of it like excel - a way of easily prototyping results from an existing Spotfire cross table.
I'd like to see each cross table have it's own set of columns just like any raw data table to make calculation reuse a lot easier. Currently I'm running these long spaghetti lines of calculations in my cross tables. Perhaps cross tables should be able to be run on already pivoted data (currently I'm having to unpivot data and re pivot it in the cross table), but I'm not really sure what implications that would cause.