Standardized Choropleth Map

http://www.statcan.gc.ca/pub/92f0138m/2008003/figures/5200001-eng.htm
The information is standardized to a certain area making it readible.  It shows the prevalence of the variable in that area.

Isohyets Map

http://www.einfopedia.com/isohyets-the-line-joining-the-areas-having-the-same-rainfall-on-the-map.php
Isohyet is the line which is used to connect the areas on the map which are receiving the amounts of rainfall.

Isobar Map

http://ww2010.atmos.uiuc.edu/(Gl)/guides/maps/sfcobs/cntr/bars.rxml

A line connecting points of equal pressure is called an isobar. That means, that at every point along a given isobar, the values of pressure are the same.
Isobars are represented by solid blue contours. An image of sea-level pressure reports and isobars has been given below.

Correlation Matrix

http://en.wikipedia.org/wiki/Correlation_and_dependence

A similarity matrix is a matrix of scores which express the similarity between two data points.  Above, "correlation coefficients between X and Y are shown when the two variables' ranges are unrestricted, and when the range of X is restricted to the interval (0,1)."

Similarity Matrix

http://en.wikipedia.org/wiki/Similarity_matrix

Bivariate Choropleth Map

http://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap171/p171.htm
A bivariate chropleth map shows two different variables at one time.  For instance, the above map shows populations AND median house value.  "Since choropleth mapping technique is designed for polygon features, bivariate choropleth maps can not be applied to point and line features."

Nominal Choropleth Map

http://www.streetgangs.com/
A map we used in class, above, shows the area of gang territories near Compton.  It's a more qualitative map then quantitative.  It shows the area of the gangs rather than how many in each area.