I teach IB - International Baccalaureate. Exams are marked "externally", meaning that mine get sent to China or Europe, where someone who doesn't know my students marks them. I started as an examiner a couple of years ago - my first year I did exams from India, Africa, and China, among other places, and the last two I've had mostly US schools. It's a lot of work, but the extra cash is nice... I get paid by the paper.