Jeff, more links for inspiration:
The graphical finesses are not quite my taste, but the animation is very informative: History of US http://www.animatedatlas.com/movie.html
I love this site: History of the 20th Century: http://users.erols.com/mwhite28/20centry.htm For instance this animation IMHO is very well done: http://users.erols.com/mwhite28/samerica.htm
Erik Zachte