Lorenz Curve

http://www.caida.org/research/policy/geopolitical/bgp2country/pics/population.png
The Lorenz Curve is a graph that shows distribution of wealth. This graph shows distribution of GDP and IP addresses across the world population.

Correlation Matrix

http://seekingalpha.com/article/97777-don-t-pull-out-of-the-markets-diversify-into-uncorrelated-assetsA correlation matrix shows a correlation between many variables. This graph shows the relationship between stock products.

Index Value Plot

http://ddo.typepad.com/An index value plot is a visualization map that is plotted on a line graph. This graph shows a company's financial index year by year.

Scatterplot

http://psyc.queensu.ca/~frostlab/sun98.htmlHere is a scatterplot that uses velocity and stopping distance as variables. This scatterplot shows the initiation of braking points.

Star Plot

http://www.answers.com/topic/spider-plot 
This star plot shows the numbers of farms of different types in different regions of England. There are many cattle and sheep farms in the South-West, whereas cereal farms predominate in the East.

Climograph

http://www2.volstate.edu/kbell/climographs.htmA climograph plots monthly average temperature and precipitation for some location. This graph shows temperatures and precipitation for Manaus, Brazil.

Windrose

http://en.wikipedia.org/wiki/Wind_roseThis plot shows how wind speed and direction are typically distributed at a particular location. This windrose plot is of the LaGuardia airport in New York, NY.