I´m looking for internet traffic rankings by most popular sites of
preferably plenty of countries.
E.g. a ranking for the United States: Top20 sites with most page
impressions, unique users or something else.

I´ve found statistics for Germany at
http://agof.de/aktuelle_rankings.365.html, showing a top20 regarding
to the unique users, but I need much more countries.

Every hint might be useful.

gg,

Alexa is the most well-known traffic ranking site on the internet, and
they offer lists of top site by country:


http://www.alexa.com/site/ds/top_500#


Click on the country name of interest, and you'll get a list of top
sites, at least according to the Alexa methods of ranking.

Let me know if there's anything else you need on this,

pafalafa-ga

Alexa is absolutly rubbish, they way they measure the traffic is
having into account the websites that Alexa toolbar users visit, so if
you do not have Alexa toolbar like most people then the visit to your
sites will not count.

To add injury to insult Alexa toolbar only works with Internet
Explorer, forget about the 20% Firefox internet users.