Hey, what a great thread... because it is one of my pet peeves, too. Well, myself, I have some backers here in Europe regarding the whole American vs. US-American thing. It's a well know fact (contrary to what the general US-American public may think) that "America" is around half of the world. Two continents and some inbetween.
Jimmoyer seems to think this thread is absurd, but its really not.. and the problem doesn't simply lie in the usage of the word American by US-Americans.. but the fact that whenever I meet an American in a nightclub, a tourist location, a beergarden, a shopping centre, anywhere you can think of here, I always ask for clarification when they say (and they always do say) "I'm from America". You know I really don't need to normally ask for clarification, because they usually have this patriotic glow and a kind of bragging attitude when they say it.
Anyhow, my response is usually "Well, America is two continents and takes up the western hemisphere.. Can you please be more specific? South, North, Brazil, Mexico, Canada??".
I've noticed that German newspapers are increasingly referring to US-Americans as US-Americans... instead of just the blanket term of Americans.