standardized choropleth

http://www.bbc.co.uk/scotland/

This is a standardized choropleth map showing the world's population density per square km.
A standardized choropleth doesn't use boundary lines (such as states or provinces).

choropleth map

http://www.water.usgs.gov

A choropleth map is a thematice map where areas are shaded (or patterned) in proportion to the measurement of the data variable being displayed on the map. This map shows the US freshwater use (in gallons per day per state) throughout the country. The most populated states (NY, CA, FL, TX, and IL) use the most.

DLG

http://oregonexplorer.info/craterlake/dlg.html

Digital Line Graph (DLG) is a digital vector data map. DLGs contain a wide variety of information depicting geographic features. This image, of Oregon’s Crater Lake Park.

DRG

http://tahoe.usgs.gov/GIS.html

Digital raster graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) standard series topographic map. This image is of Lake Tahoe.

Bivariate Choropleth Map

http://gis.esri.com/library/userconf/proc99/proceed/papers/pap171/p171.htm

A Bivariate choropleth map shows two different variable on a choropleth type map. For instance, this map shows the population by county AND the median house value by county in the state of Ohio.

nominal area choropleth map

This is a choropleth map using nominal data (different classes) showing the percentage of Latino/Hispanic citizens in Florida counties.

DOQQ

http://www.lacoast.gov/maps/2005doqq/

DOQQ (digital ortho quarter quads) are aerial photos that have been corrected so that the pixels are aligned with longitude and latitude lines, and have a narrowly defined region of coverage. This DOQQ image is of Louisiana.