Neat little program that puts a graphical representation of the Earth on your desktop. By default, it shows the location of major cities and rotates in time with the planet.
Has a extensive set of options, including (BNLT): the position of the camera and the sun; the rotation of the Earth; the magnification; and the frequency, density, and size of background stars.
Created by Kirk Johnson.
http://www.cs.colorado.edu/~tuna/xearth/
Editor's note: This link no longer works.