
A nominal choropleth map is a map that displays a unique value.
A univariate choropleth map is a choropleth map that displays a single attribute.
http://www.biomedcentral.com/content/figures/1471-2342-6-12-5.jpg
The correlation matrix computes the correlation coefficients of the columns of a matrix. That is, row i and column j of the correlation matrix is the correlation between column i and column j of the original matrix. The diagonal elements of the correlation matrix will be 1 since they are the correlation of a column with itself. The correlation matrix is also symmetric since the correlation of column i with column j is the same as the correlation of column j with column i.




Distribution of salaries of the Acme Corporation
This is a scatter plot of the initiation of braking points relative to target (start of maximal deceleration point in braking) for subjects riding the bike at different perceived velocities. 




This is a clipped portion of the NW quadrant of Union Springs, NY.
DEM map of Salt Lake City West, Utah
DLG map of 1:2,000,000-Scale DLG data of the Illinois and Missouri States. 
Isopach Map of Holocene Overburden




Infrared aerial photo of the Sacramento Deep Water Channel 



Distribution can be shown as a dot distribution map. These show population concentrations well but can give the impression some areas have no people.
Japanese propaganda caricature map from around 1941, depicting a U.S. blockade of Japan from the Philippines which at that time was a United States possession.