I have entered the US market! I've made a Simple Little Map of New York. It's similar to the maps of London, Dublin etc., however I've used a new 'auto-zoom' feature, where areas that have a high density of 'stuff' are show zoomed in. This way city centres can have more pages to themselves.
I previously said that I was focusing on the european market for now due to concerns over how to get paid, however I can't change Amazon, they will pay me in cheques. It'll be a pain to have to wait a while before I have $100 in royalties, however I want to earn more than $100 per month with Kindle-Maps.com, so in theory I shouldn't have to wait more than a month. The US is (I assume) a much larger market than the UK.