Dot distribution maps

http://www.mobot.org/jwcross/duckweed/Habitat/geography.html

This map is a good example of a Dot Distribution Map. From the website it states "Each dot indicates an area of duckweed occurrence." Dot Distribution maps are good for displaying populations, locations of events over time, and other data over a geographic space. They can be simple to produce, one dot to one event, or more complicated, one dot equals 1000 events.

Another cool example is the video of world history according to wikipedia. A dot is used for each entry into wikipedia.
http://gizmodo.com/#!5783985/wikipedias-history-of-the-world-visualized