That's an amazingly interesting discussion you're having here!
I really regret I haven't joined earlier (I thought it's a thread about today's mass American culture or something like that).
There were too many great things said, for me to quote all of them. I like especially what presented
Athenian and
Haphazard .
I'll try to briefly point out what I see as 'American culture' and what is American input into world's culture.
So first of all I think you're selling yourselves a bit short. Because America had a pretty amazing influence on world's culture and lifestyle.
1. Literature
-> Walt Whitman - it was the first poet to write this way, he basically started a revolution and have launched poetry to a completely new sphere.
-> Thoreau - he was a part of Romanticism movement, but he pushed it further into individualism and love of nature. Also combined his thoughts with politics (like Emerson), which launched a new wave of 'engaged' prose
-> Mark Twain, Sherwood Anderson, William Faulkner, Ernest Hemingway, Thomas Pynchon - each of them was an innovator on a world's scale. There was a time when everybody was copying Hemingway.
2. Music
There's just too much to write. America was a pot (only one in the World) where the African culture blended with the European one. Result: Jazz, Blues and Rock'n'Roll. The whole today's popular music basically comes from US roots.
3. Cinema
I'd say the role of Germany and France is downplayed in general, but there's no doubt that popularizing Movies and making it the 'number one' entertainment is something America did.
Hitchcock invented 1/2 of the camera techinques that are used in today's cinema. (one of the most amazing examples - the thing one camera surrounds characters the way it looks like the world is whirling around them)
4. Lifestyle
We all live in America today...
It's Henry Ford that made world one big highway. It would never be a European invention - we have to old and to small cities for that. Automobile for everyone was invented for a country with vast spaces, with everything far apart.
Supermarkets - again, totally American. We have thousands of little shops and everything within walking distance. You have to take a ride to go to shop ANYWAY, so it can as well be huge.
We have it, because you had it first.
OK, I'll resign from posting MORE things like that otherwise it would end up as a book.
Now I want to add what is amazing for a European, when you look at America. And it is: POLITICS.
I mean, the idea of local representation, the idea of people rallying together to create something (OK it happened in Greece, China and... Poland

long time ago, but you took it to another level) is your invention. There's an amazing book called 'Democracy in America' by Alexis de Toqueville and nevermind that it was written in XIX century - it's still the best book to understand your society, I think. He has written:
'Whenever there's something that need to be done for the good of society, a Frenchman will address his government, an Englishman will look for a rich noble to make it done, while an American will organise a group, a committee to take care of it.' It's amazing. You guys have THOUSANDS of committees, you believe it's up to you to make something happen! All this: 'Mothers against drunk drivers', 'Parents against pornography' - for a European it's just AMAZING. I think it's the biggest asset of American Culture, it provides an amazing social capital and also binds people (also immigrants) by constant group effort for the betterment of society. You cannot be 'alienated' and completely stick to your own culture if you're constantly pushed to act together.
I'd also add the idea of '12 angry man'

- taking part in the justice process.
As one of you (Haphazard?) have mentioned: America is about l local community, the local organisation. I think it is the core, the heart of America.
Amen!