I've coded in localisation support for this site, so it can automatically detect your preferred language, and display content in that language if it's available. Dialects are supported, so in English you can get your preferred spelling of “favourite colour”.
Most of the site has not been translated into other languages yet, but I've translated a few bits and pieces into Spanish, and dates should work correctly for several languages. If you'd like to help me translate, send me an e-mail and let me know what you have in mind! I'm not in a big hurry to translate anything.