Tild is trying a little experiment, seeing how much international audience is attracted by US blogs of the Left and Right. So far, on the Right, Powerline with 6%. On the Left, Tild has 32%. PZ Myers of Pharyngula has 43%. Here, my blog has 41%. Do the same thing on your sitemeter and report to Tild and PZ.
Here are some others from the Left:
Legal Fiction - 13%
Majikthise - 29%
Pandagon = 19%
Shakespeare's Sister - 22.25%
Eschaton - 5%
Bitch, PhD - 22%
I guess it depends how much a blog is narrowly focused on US politics. Blogs that touch on other topics (e.g., science, feminism, religion, etc.) may have a more international audience.
OK, from the thread on Pharyngula, comes information that Sitemeter tracks only a pretty small number of recent visits (perhaps last 100 hits, thanks Norwegianity).
Some hits are from spam-bots, some are just random - blogexplosion, "recently updated blogs" on Blogger and other places, clicking on "Next blog" in Blogger, or even Google searches, etc. Having a large regular audience dilutes these as a percentage of overall visitors. Stats from a smaller blog would be more strongly affected by such random hits.
Thus, one should expect to see a U-shaped curve, the proportion of international visits being high when checked at midnight (in the USA), dropping to a low at noon (while most of the rest of the world is asleep and Americans are checking blogs during lunch-break), then rising again to a high at midnight. My %foreign dropped from 43% in the early morning down to 21% about 4pmEST. I'll see if it goes up again tonight.
Stats from a large blog will track only the visits from the past few minutes, thus exaggerating the U-curve. A blog that gets about 100 hits a day should remain pretty constant over time, and even smaller blogs will be immune to the U-curve entirely, but will be more responsive to spam and random hits, thus fluctuating wildly.
More bloggers have posted their results on the Pharyngula thread, Tild thread, or on their own blogs (you can find them with Technorati searching links to those two threads, or to this post here)
Update 2: Ha! Found a US-based blog with MORE than 50% foreign readership: East Ethnia