I saw Joel Parish’s Ajax Translator on Ajaxian last week. It’s an on-the-fly Ajax application that creates real-time translations between English, Spanish, German, Italian, Portuguese and French. Very slick.
Ajax Translator, like Babel Fish, is useful for crude communication that translates one word at a time or that has the same grammatical structure in both language, but it does not allow for grammatical inconsistencies. For more complicated communications the back end quickly falls behind.
The front end is cool though.