Where can I find information (ideally in a concise format) on the
U.S.A.'s contributions to the world in areas such as art, science,
business, politics, international development and culture. This can go
as far back in history as you like, but should at least cover the 20th
century. Please exclude as sources any encyclopedias, including
wikipedia.org. If there are no resources that cover this information
overall, I would also be interested in resources covering only the
specific areas listed above.

The main Contributions of the U.S.A to the world are Coca Cola; fast
food a la MacDonalds; processed cheese; Broadway and Hollywood
Musicals; mass production techniques; nuclear bombs; computer
technology; and Pinkfreud.

Um, we DID walk on the moon. That led directly to microwave ovens.

I'm sure the Russians walked on the moon first but they were so modest
they didn't tell anybody

Microwave ovens have been around since 1947, so I doubt if they were a
spin-off of the moon program

If Mark says that he walked on the moon, I believe him. And who's to
say that Mark didn't do it before 1947?

I guess that this probably occurred during WWII when secrecy was
paramount and, on his return to Earth, Mark then invented the
microwave oven.

Well done, Mark, and congratulations on both your bravery at making
that single-handed balloon ascent and your inventiveness in also
making the first microwave oven.

But credit must also go to Nikola Tesla whose experiments pointed Mark
in the right directions: skywards to the moon and earthwards back to
his own laboratory.

As we all know, Mark is that rare type of American: modest, painfully
shy and self-effacing. Not at all like Lindberg.

A bit like me ... although, of course, I'm not American.

Bryan

*snort* A balloon? I'd expect a guess like that from the French. No,
the way ya get to the moon is to sail to the edge of the Earth on a
night that the moon isn't showing, 'cuz that means it's hiding
underneath, and sail off the edge. You need a parachute to float down
to the moon. Then when the moon is up in the sky you just jump off and
since the gravity is so low up there you start falling to Earth. Using
a second parachute, you float down.

The paratroop drops of World War II were used to cover this secret mission.

As for the microwave ovens, several were found on the moon. They were
pretty ugly things with fake wood grain and avocado coloring. In the
late 50's team of defense contractors led by a young Donald Rumsfled
invented the 1970's (which hadn't existed before the Apollo program)
so their companies could exploit the reverse-engineered alien
technology, which is little more than a teeny moonman with a phased
plasma gun.

It is tempting to make less than serious suggestions to your question 
- as my friends here have -  and tempting to me, too:  the airplane,
morse code, etc., etc., although other countries make counter claims.
I do believe that Edison invented the incandenscent light bulb  (and
most of the world still uses the same 1 inch screw fixture  - and the
1 inch crown bottle cap).  And Ford did invent the production line. 
(Or did he?  I think the Venetians were building galleys on a similar
principle centuries earlier.)

The US Constitution is a landmark in national governance.  There were
earlier codified laws, but it was/is a more complete definition of the
separation of powers for a democratic system of government and has had
an influence on almost all such that followed.