I'd love to do exactly that, but right now I get my popularity stats from English-language Wikipedia pageviews, which is majority-influenced by the US but also has significant traffic from India and the UK.

If Wikipedia ever breaks down its pageview stats by country, so I can generate different quizzes per-country, that's the first thing I'll do!

Not to nag you, but have you seen my suggestion of using the number of translations of each entry as an indicator of their cross-cultural value? What do you think if it?