Some of the most interesting maps are those which show extreme changes in a particular area over a given time. One such example of this surrounds the visualisation of Australian Bureau of Statistics (ABS) Census data. There are many depictions of how population, housing affordability and household family composition has changed over the years. Granted, this data can be shown as simple statistics in a table, but where the real power lies is in visualising this data spatially. By showing change over time through a map, the user can start to make observations, and perhaps, draw conclusions from what the data is showing us. Like all scenarios, generally, you will have a high proportion of data which sits in the average/median grouping where some change might have occurred, but then you will also generally observe some outliers which are "extremes" from the median. That's why it's always a good idea to always normalise your data in order to show variances from the total.
Using the ABS data, one could make a map showing snapshots of raw (total) values. For example, we could have a look at the distribution of Melbourne's aging population (65 yrs and older) over the last three census years (2006, 2011 and 2016) as shown below: