In 1990 the Deutsche Post celebrated the 125th Geburtstag of seminal German comic heroes Max Und Moritz by publishing one of the very few comic-related sets in their history. Four stamps were published, featuring scenes from the comic book by Wilhelm Busch in 1865. Above is a self-addressed envelope from the day these stamps were published, featuring the First Day Cancellation. I won it on Ebay around Christmas, and it was a bargain as well.
An online version of a 1925 Max Und Moritz reprint can be found at Children Books Online.