A fascinating article on the BBC website today looked at British English words and expressions creeping into American English - like spot on, chat up, sell-by date, gastropub, twee and chattering classes. Another example is ginger, meaning red-haired, which became more popular in American English after the publication of the Harry Potter books.
Sometimes British English terms have taken off because they seem to fill a gap in American English, according to the American editor of the OED, like one-off and go missing. Sometimes Americans use the British term - university instead of school or college, for instance - when they are outside the US and want people to be clear about what they mean.
It's not just British words that are becoming more popular in the US. Professor Ben Yagoda of the University of Delaware has noticed his students using the glottal stop instead of a T, a feature of the London accent. He has also noticed a trend towards adopting the British way of writing dates - day/month/year, rather than writing the month first.
The article is well worth reading, regardless of the variety of English you speak. Thanks to Helen and Elizabeth for sending me the link.