Esperanto in an created language made with the specific intent to be easy to learn, and to be the primary secondary language for international community. It is very easy to learn and is a language that is currently supported by the UN and Google, as well as other international organizations. It is devoid of national and cultural associations and will be less likely to change once accepted like French did to English following World War II (if I remember correctly).
The basics can easily be learned in a semester or two and studies have shown that those who learn it find it much easier to learn and understand other languages.
With most people having learned Esperanto we would only need to translate documents and subtitle movies and so on into one language - Esperanto saving millions of dollars for companies, as well as increasing is ability to be understood by people around the world.

http://en.wikipedia.org/wiki/Esperanto