Site made by Yoda_57, with pictures:
http://aidepc.online.fr/mercedes/

List of produced Ponton (W120, W121, W105, W180, W128) models:
http://www.mbzponton.org/valueadded/other/overview.htm#production

Production of more old models:
http://www.autogallery.org.ru/pmbtable.htm

The German Wikipedia article is quite complete too:
http://de.wikipedia.org/wiki/Mercedes-Benz-PKW#Produktlinien

This site lists some older Models:
http://www.philseed.com/mercedes-benz.html