The "Clusters" and "Bubbles" display settings for Map-based charts are useful for grouping together many data points on the map. The toggles for these settings can be found in "Map Display Settings" on the right of the "Chart Format" tab:
The "Clusters" setting will split the points into discrete clusters, with each cluster displaying its number of points. Clusters will only count duplicated points once. Hover over a cluster to see its bounding polygon:
The "Bubbles" setting will group the points into finer-grained sets of overlapping bubbles, whose size is proportional to the number of points contained:
The weight of bubbles can be controlled by adding a third column explicitly aliased as "weight".