I built this: translate.songbirdnest.com You don't see flags on the site, but in the language package you download, there are flags. I can't remember if we used to display the flags on the site - it's been redesigned since I left. 1. US citizens are not annoyed by the UK flag. As someone else pointed out, if someone in the US sees a British flag they will probably think the site is not for them. I don't think it work…
Personally I'd try and go for a dropdown list of language names in that language - probably choosing the default selection from the UA string or the accept-language; then keeping the language setting in a cookie.