Don't forget also the "circus" song: http://en.wikipedia.org/wiki/Entrance_of_the_Gladiators

the "camping" song: http://en.wikipedia.org/wiki/Dueling_Banjos

the "end of the world" song: "O Fortuna" from http://en.wikipedia.org/wiki/Carmina_Burana_(Orff)

the "nautical" song: http://en.wikipedia.org/wiki/The_Sailor's_Hornpipe

the "Italian" song: http://en.wikipedia.org/wiki/Tarantella_Napoletana

the "morning" song: "Ranz des Vaches" from http://en.wikipedia.org/wiki/William_Tell_Overture

Just the first couple seconds of any of those songs are universally recognizable and commonly used to set scenes.

I wonder, is there a stereotypical "American" riff used in Chinese media? The beginning of "Yankee Doodle" or something?