Correlation matrix.

https://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_ods_sect017.htm

This graph displays the rating of automobiles in a correlation matrix. This displays the relationship between the rating of certain components of automobiles, displaying corresponding values under each column. Qualifying as a correlation matrix, it contains correlation coefficients among several markets in different timeframes.

Bivariate choropleth maps.

http://www.geo.unizh.ch/~annal/Choropleth%20maps.html

Bivariate choropleth maps combine two datasets into a single map allowing a graphical representation amongst a group. The map above displays different color representation showing the percentage of population under the age of 18. The map displays spatial distribution of the two groups, using the colors to distinguish accurately.

DRG Map

https://www.e-education.psu.edu/natureofgeoinfo/c6_p6.html

DRG maps are scanned raster images of USGS topographic maps. Above is a DRG map of Bushkill, PA, showing lakes rivers and streams with the use of contour lines to represent elevation. DRG maps are often used when other digital data is superimposed. therefore the accuracy of a vector file containing these lakes and rivers can be checked by plotting it over a DRG.

DLG Map.

http://www.mapcruzin.com/free-geodata-shapefiles/usgs-geospatial-data-geodata-geographic-download.htm

Above is a DLG map of a region with a scale of 1:24,000. DLG maps are line graph data with digital representations of cartographic information, with the use of digital vectors. The lines above are distinguished by different colors; a format that represents spatial data for the transfer between computer systems. 

DEM

http://www.satimagingcorp.es/gallery/dem-sahara-tunisia-lg.html

DEM maps are a digital elevation model of a terrain's surface. This map shows the a DEM image of the Sahara desert, with the use of contour lines mapping out elevation levels amongst the desert's surface. DEM representations can include terrains of the Earth, Moon, asteroids, etc. DEM maps represent how accurate the elevation is, including factors such as terrain roughness, grid resolution, and vertical resolution. 

Isopleths Map

http://dwb4.unl.edu/Chem/CHEM869V/CHEM869VLinks/weather.about.com/newsissues/weather/library/weekly/aa071600a.htm

The map above displays hydrogen concentration as pH measurements made at field labs in 1998. The rainfall is collected and measured in terms of pH to determine the general effects of acid rain, along with SO4 and NO3 concentrations. With distribution across the U.S, it qualifies as an isopleth map due to it simplifying information about a region.

DOQQ Map

http://www.utexas.edu/depts/grg/hudson/grg360g/EGIS/final_project/spring04_projects/web_justin_reynolds/Lake%20Travis.htm

DOQQ maps are digital orthophoto quarter quadrangle maps created by the U.S Geological Survey. It is an aerial photo that has been pixelated alined with longitude and latitude lines. Above is a lap of Lake Travis, narrowly defining the lake's region, a technique used in DOQQ maps called rectification.