Arrays as source data for Data Validation, Pivottables or Sparklines
It would be nice if more of the user commands in the Excel object model allowed arrays in addition to cell references as inputs. We could then set a user defined function (vba or xll) as source in these situations which updates dynamically.
We can already enter arbitrary arrays in charts and names from VBA, but other functionality such as data validation, pivottable source data and sparklines only allow range inputs which necessitates use of hidden sheets and dynamic references.
This would be great for interaction with office-js, being able to dynamically retrieve valid options from a custom function.