The ability to automatically bin values in maps.
This would allow users to control how sizes and colours are assigned to maps, giving much more control over the way the maps look.
Users would ideally have following options:
Equal sized ranges
User specifies number of ranges and VA automatically calculates the boundaries and groups items
Custom ranges
User specifies the boundaries for ranges to use as bins
Equal sized bins
User specifies the number of bins and VA automatically calculates ranges that group equal numbers of items together.
Standard Deviation
VA calculates the median and then sets ranges at 1 SD intervals
All above options would need to work dynamically and auto adjust if the user filtered the map content.
Below is a screen grab from a popular GIS that offers this functionality
