It would be cool to make a parameter visible based on certain conditions (with a formula?). In that way the end user of a Revit family, for example, sees a yes/no parameter based on formula driven conditions through a formula.
The problem we're now facing (for example) is we have a yes/no condition, whicih is applicable for a product within 2 diameters (out of for example 10 diameters). You could inform the end user about that through the tooltip, but make the yes/no visible only at those parameters would be extremely cool and useful.